**Originally published on 6/26/2015 – updated on 2/12/2018

Gmail uses many different algorithms to determine inbox placement as well as delivery of your messages. Those algorithms use countless points of reference such as engagement, complaints, bad addresses for a combination of sending subdomain and top domain, bounce domain and DKIM, IP address, body content, branding, source coding, etc. Therefore when you have an issue, troubleshooting can be overwhelming. Below are the top 15 best practices you should follow in order to avoid issues to begin with when sending to Gmail.

  • Opt-in. Gmail strongly suggests double opt-in or confirmed opt-in when possible. However, single opt-in is a must. It is important that each subscriber opt-in to the exact message stream they are receiving. It is not enough that they opt-in for your type of message. For example: Katie opts-in to receive messages sent by JobSiteA. This does NOT mean that JobSiteB can start sending Katie messages simply because it is the same subject matter or even owned by the same parent company of JobSiteA. Katie has to explicitly opt-in to JobSiteB’s messages.
  • Engagement. The most important thing to remember is to send messages to subscribers who are engaged with your brand. They are opening, reading, clicking and interacting with your brand. Interacting may mean purchasing or even getting involved with the discussion depending on your business model. Develop a list hygiene process to remove non engaged subscribers from your active sending list on a regular basis.
  • Overall list hygiene. Do not continue to send to email addresses that no longer exist or hard bounce (SparkPost suppresses hard bounces). Do not continue to send to subscribers who have not opened or clicked in a reasonable time. This length of time really depends on your business model. A good rule of thumb is that actively engaged subscribers will open and/or click on your daily messages at least once in a 30 day time frame and at least once on your weekly messages within 90 days. Any subscriber that has not opened or clicked on your messages in the past 12 months should be permanently removed from your list as they run the risk of becoming a spam trap.
  • Monitor blacklistings. Gmail does use 3rd party blacklists (which ones are unknown) to determine inbox placement.
  • Avoid URL shorteners. Gmail will block most of them if used in bulk mailings, especially bit.ly.
  • Use the unsubscribe header. Make it easy for subscribers to unsubscribe from your message! Spam complaints are not shared back to you through feedback loops like other ISPs. Therefore it is crucial that your subscribers unsubscribe rather than reporting as spam. SparkPost deploys the list-unsubscribe header and suppresses unsubscribes.
  • Avoid affiliate marketing. Gmail states you should avoid affiliate marketing as a tactic. It is also against SparkPost policy to send affiliate marketing through our system.
  • Authenticate. Authenticate with both SPF and DKIM.
  • Subdomains. Use different subdomains that define your different email streams. (Example: newsletter.example.com; deals.example.com; confirmation.example.com) Be consistent. Don’t add too many as you want to be able to develop a reputation for each subdomain. However, remember that the top level domain reputation is also important.
  • Configuration Warm up. In general, warming up IPs or domains when there is a change are what marketers focus on. However, Gmail ties reputation to the entire DNS configuration during warmup. The reputation is tied to the collective SPF, DKIM, IP setup, domain, ect., therefore it is imperative that you have your configuration set and locked in before you start sending. Once it is complete and verified by testing do not make any changes unless you are prepared to do another warmup for the new configuration. In the chart below, we provide some best practice warm up guidelines as you introduce your traffic into the GMAIL network:
    • Gmail Warm up Volumes.
    • Engagement. The key is to send to the most active first then add in the lesser engaged as the volume builds over time.

Promotions vs Primary Tabs

Due to the introduction of folders, subscriber traffic can now be delivered to additional locations and not solely the inbox or spam folder. It is not like the scary wasteland of lost messages called the SPAM folder. If you have an interesting subject line and a brand that your subscribers want to engage with, the promotions tab will still get you opens and clicks.

  • Per-user filtering. Remember that just because some subscriber messages may be in the promotions tab does not mean that all subscriber messages are in the promotions tab. Filtering is done on the individual subscriber level not bulk sender level.
  • HTML to Text Balance. Keep the balance of HTML to text similar.
  • Encourage Interaction. Subscriber awareness is important. Train your subscribers to expect the message and move the message into the Primary tab. The messages should start going to the Primary tab after a few moves.
  • Don’t send a promotion. When the above fails and you need a message to get into the inbox design your message to NOT look like a promotion.
    • Personalize your messages. Include the reader’s first name in your message to Gmail subscribers.
    • Lose the images. Gmail sees images as a sign of a promotion or spam message. You will increase your readership by not having pictures.
    • Letter format. Design the Gmail template to look more personal and natural like an email.
    • No obvious calls-to-action. The best way to keep from looking like a promotion is to have no more than 1 link and no upsells or RSS Feeds. Keep it short and simple like talking to a friend.
  • Appreciate the promotions tab. When it comes down to it, if a subscriber wants your message in the primary tab they can move it there and will receive it there after a few moves. However, Gmail’s tabs are not new and subscribers know how they work and often go to that tab for promotions they are interested in. The promotions tab can actually work in your favor. For example, if a subscriber is very involved in social media and receives a large volume of social media notifications, marketing messages can get lost in the inbox and separating them out to the social tab can actually be a plus, which leaves your message to be seen at the top of the promotions tab easily found by your engaged subscriber. Just remember that if you send your subscribers what they want and leave them wanting more they will go to that promotions tab to see what you have to say!


Insights from Marketing Sherpa & The King Freak Himself: Stephen J. Dubner

capuchinThe Marketing Sherpa Email Summit is winding down in Vegas; the attendees around me have a kind of ‘thousand yard’ stare from what’s certainly one too many late nights. Those that were in attendance for this morning’s keynote have the same stare but are also walking a little taller and filled with the kind of rich data driven storytelling knowledge that only Stephen J. Dubner himself can impart.

Mr. Dubner’s keynote covered a range of topics, and when I say a range I really mean a range: we moved from competitive eating and the birth of a hot dog champion, to economic monetary models built on teaching Capuchin monkeys the value of money. Anyone familiar with Mr. Dubner’s podcasts or the documentary Freakonomics knows that he’s a data-driven storyteller that squeezes insights from the most unusual places.

In his own words: “we’re good at measuring the what, but we rarely know the why.” To me this means that the difficult part isn’t necessarily the testing, but understanding the intention underlying the results. How does this relate to email and messaging? Well let me go back to something else he said: “think differently and redefine the problem you’re trying to solve.” The most successful practitioners of email routinely approach the challenge of how to better communicate with their customers with equal parts imagination, scientific testing and something that smacks of shock and awe. Repetition without invention or iteration is bound to disappoint and be dismissed in a world where information and messaging is around every corner.

This leads me to consider another point: “the right answer isn’t necessarily the best answer.” Solving a problem isn’t the same thing as innovating a solution that changes the nature of business, or the dialogue and experience between customer and brand  facilitated through email or other forms of messaging. Playing off of that, let’s throw this concept onto the pyre: “break down mental barriers, don’t pledge allegiance to the way things are done because everyone else does them that way.” Think about the emails that really catch your eye, or the brands that create a name for themselves: do they follow the herd or do they lead it?

Mr. Dubner’s approach holds a great deal of possibility above and beyond the intersection of psychology, economy and sociology. The doctrine of Freakonomics, as it was dropped on us was simple: “don’t be afraid to ask ridiculous and irreverent questions.” Innovation doesn’t happen unless you’re ready to really break the norms and conventions that define what you think you’re doing, or what you assume is the normal way of doing it.

Here’s one solid relevant example of doing things differently. A few weeks ago at the Email Evolution Conference, Sri Somanchi from Google’s GMail team advised that mailers ramp down messages to unengaged users. We’re all familiar with the concept of IP warm up/ramp up in terms of volume to build a reputation for a new IP, but have you ever considered how volumes need to be cranked the other direction when your emails are deleted and never opened? Sri’s advice is to switch from daily to weekly, if the recipient continues to let the emails go unopened, then send a final re-engagement email and stop mailing all together. This is the same advice that Sri has given to the Google marketing team. If we stop and think about what Sri’s doing, he’s approaching the problem in the simplest of terms: if someone wants the message they’ll open and read it, if not, there’s no reason to send it. The accepted wisdom is to never have an expiration date on messaging, keep sending, don’t stop—maybe, just maybe, this bit of counterintuitive advice fits the mold of irreverent thinking, maybe even heretical depending on which side of the fence you stand on. It’s a solid piece of advice and from an insider, someone deep in the trenches of email. So go on, give yourself carte blanche to do things a little bit differently.


deliverability_panel_eecI’m in Miami wrapping up #EEC15, The Email Evolution Conference. The closing Keynote Panel Discussion organized by Dennis Dayman and Ryan Phelan was worth the price of admission; the panel they organized featured key postmaster/abuse personal from Comcast, Hotmail/Outlook, AOL and Gmail. Although regular fixtures at M3AAWG meetings, the folks in this room don’t normally have a chance to hear first hand how an ISP measures activity within the inbox and responds to emails as they arrive. There were furrowed brows, heads nodding and a plethora of other emotions as questions were asked, assertions made, accusations levied and laughter enjoyed by all.


One of the most important things I took away from this session and I think you may find this valuable too are the signals that most ISPs read as good vs. bad. Here’s a cheat sheet and take away that you can help you better understand how engagement, which was called ‘a philosophical principle rather than a secret sauce’, is measured by a mailbox provider or an ISP. One of the major disconnects I’ve seen between senders and receivers is the idea that engagement is a single measure. Quite the contrary, senders are not privy to the metrics that receivers are and vice versa, there may be some attribution, analysis through web behavioral data, that leads to a very different picture of engagement on the sender side. This is the fundamental conundrum that I think is best represented by the metric system vs. the english system. Both are valid (well one’s more practical than the other), both are capable of measuring the same distance but use different units. One doesn’t invalidate the other, hence the philosophical nature of the construct.

Positive Signals

  • Open an email
  • Adding a sender to the address book
  • Moving a message to a specific folder (filing)
  • Rescuing a message from the spam folder
  • Replying to a message.

Negative Signals

  • Deleting a message without opening it
  • Marking a message as spam
  • Reporting phishing

Thankfully there are more positive signals that inform engagement at a mailbox provider than negative ones. One thing to consider: I’ve seen a number of senders instruct their recipients not to reply to an email, that the email box will not be checked or monitored. Given that replying to emails is a positive signal that will ultimately improve a sender’s engagement, leading to better reputation and finally deliverability, it might be worthwhile to make the sending addresses accept replies and even review them for customer correspondence.

Gmail introduces a pilot feedback loop offering

Back in February, Gmail announced their Feedback Loop (FBL) pilot offering to ESPs to help them with identifying bad actors and spammers on their network. For anyone who is interested in learning more, the enrollment form can be found here.

For those of you who are unfamiliar with the process, here’s a brief recap. Feedback loops are essentially reports that ISPs provide to large volume senders about the number of recipients who mark their mails as spam. It’s a really important service that allows businesses to monitor their sender reputation with the ISPs and quickly take action for damage control if large numbers of recipients are marking their emails as spam. As you can already tell, this is pretty crucial for businesses that are dependent on email marketing as a main revenue stream. 

Gmail’s feedback loop, however, differs from other ISPs 

Gmail’s FBL is not in ARF format. In order to protect user privacy, their FBL is offered in the form of aggregated spam statistics per customer or per campaign, which cannot be traced back to the email address of the recipient who marked the mail as spam. This daily report provides a percentage of user spam complaint rate per customer and/or campaign of an ESP, and will be sent to the designated email address provided to Gmail by the ESP (eg: [email protected]). The service is not designed for list management or delivery evaluation, and if there is a sizable percentage of spam in your traffic, you will receive the aggregated report the next day.

ESPs are highly encouraged to comply with Gmail Bulk Senders guidelines. Gmail requires all senders to use a consistent IP address to send mail, valid RDNS record for all sending IP addresses, and the same address in the ‘From:’ header on every bulk mail. As far as authentication, they highly recommend signing with DKIM, publishing an SPF record and adhering to the DMARC policy.

How does Gmail’s feedback loop work?

ESPs will first need to insert a feedback identifier header “Feedback-ID”. This header will identify the customer and or campaigns, mailings, and mail types. FBL reports will be generated based on these identifiers.

The “Feedback-ID” header will have a maximum of 4 fields, 3 are optional.

“Feedback-ID: a:b:c:ESPid”

  • “Feedback-ID” is the name of the header
  • “a:b:c” are the optional 3 fields which can be anything the ESP chooses (ie: campaign, mailing, traffic type)
  • “ESPid” is the only required field. This ID corresponds to an ESP customer and must be unique and persistent to that customer.

Gmail will aggregate data for the last 4 fields starting from the right side and ignore any extra fields. The data returned in the feedback report will be aggregated by the tag seen in the Feedback-ID header. Every tag will be included in the report and there are no limits on the number of total tags specified. However, Gmail will ignore tags with too few messages to prevent abuse.

Date Identifier Spam_Rate



















FBL data will be aggregated by way of each identifier independently and not grouped across identifiers. Spam percentages will be reported across all the mails containing a given identifier, irrespective of the position in the identifier header. The FBL report will be sent in the form of a CSV attachment and contains data received by Gmail on the previous day by the ESP. This report is intended for gmail.com users and doesn’t support Google-Apps or Google hosted domains.

What are the DKIM requirements?

To prevent spoofing of the “Feedback-ID” header the ESP must strip any instances of this header first before inserting it and then DKIM sign it with the ESP’s domain key. This is in addition to any existing signature and is a practice commonly known as “double signing”.

There may only be up to 10 unique DKIM “d=” signing domains used to sign these headers but subdomains may be used as an alternative.

As far as DKIM key length is concerned, Gmail requires a minimum 1024-bit long key. According to the Gmail postmaster site, Gmail has been treating all emails signed with less than 1024-bit keys as unsigned since January 2013. They recommend affected senders with short keys to switch to RSA keys that are at least 1024-bits long.

How can we correctly implement Gmail’s FBL requirements in Momentum?

Multiple signatures are supported in the Momentum platform using Lua policy. OpenDKIM is now the preferred signing module in Momentum versions 3.6.0 and newer. More information about the Lua libraries for signing can be found in our documentation.

We’ve also created a simple OpenDKIM signing Lua policy that easily configures a second signing domain. You can find more info about that here.

Which Other ISPs Provide Feedback Loops?

If you’re looking for more information on how feedback loops operate, do refer to the “Complaint Feedback Loop Operational Recommendations” RFC 6449 document. And while we’re talking feedback loops, it would make sense to share links to the other trusted FBL providers out there, in case you didn’t have them already.

Now, to sum up: it’s great news that Google now provides an FBL. It has some quirks and senders will need to do some configuration to get it to work for them. But for Momentum users, that will be a straightforward process. If any readers would like to share their experience with the new Google FBL, we’d love to hear your story. Feel free to leave feedback in the comments.


–Kate Nowrouzi
VP, Email Delivery Operations

Weekly Email Marketing News Digest

We learnt about how social and email both played a unique role in the sales funnel last week. This week, it’s all about the email inbox, from email metrics, to email deliverability and how to get into the inbox, to Google’s new tabbed inbox.

TINS: The New Email Metric?

This Is Not Spam Rate could be the shiny new metric for email marketers and provides great insight into deliverability. A brand with a deliverability rate of 88 – 97% of emails had an average TINS rate of 0.15%. Brands with 97 – 99% deliverability had a TINS of 0.44%.

13-18% of emails that are read have a 0.34 TINS rate while emails with a rate of 22% and higher had a 0.97 TINS rate.

Few people take the time to go into their spam folder and fish out emails that are not spam unless they are transactional emails from financial institutions that people are actually looking for. If your brand’s emails are being removed from the spam folder by subscribers, it’s a clear indicator of engagement.

Increase the Value Of Your Abandoned Cart Emails

Customers are wising up to the offers that retailers are providing to get them to convert. Here are two considerations:

1. Ask yourself if you should send an abandoned cart message. The answer should hinge on these concerns:

  • Has this customer received an abandoned cart message in the past XX number of days?
  • Does the cart value exceed a certain amount?
  • Is this a first time purchase?

2. Is it necessary to include an offer in the abandoned cart message? Sometimes a product review might work just as well as a discount.

Are Gmail Tabs Hurting Email Marketers? Let’s Find Out!

The new Gmail tabs that sort your emails into Primary, Social, Promotions, Updates and Forums have been widely proclaimed  as the death of email marketing. Not so, says our good friend and technology marketer, Chris Penn. To find out if the new tabs are actually hurting your email metrics, Chris recommends pulling the following statistics:

  1. How many Gmail addresses you sent to that campaign?
  2. How many of those Gmail addresses opened the email?

The answer might surprise you, but don’t buy into the panic before pulling those statistics.

25 Mindblowing Email Marketing Stats

Salesforce has a list of 25 email marketing stats that you can use to convince anyone of the power of email. Here’s one of them:

“64% of people say they open an email because of the subject line.”

Now you have all the ammo you need to convince your team to invest in email.

Deliverability Check List

Here’s a checklist for email campaign delivery:

The Email Check List

Find out more about how to get your emails into the inbox when you watch The Keys to Deliverability Success webinar!

Keys To Deliverability Success Webinar

Weekly Email Marketing News Digest

Great start to 2013… and the second post of the year for our email marketing news series! From tactics, predictions and new technological email features, there’s a little bit of something for all email marketers.

Email Marketing Basics: 4 tactics of the incredible email marketer 

Good email marketers know that email marketing is great for lead nurturing and stretching your customer lifetime value. Incredible email marketers know the cool tactics that will drive customer engagement and clickthrough. Here’s how:

  • The Reward Delivery – Everyone loves a freebie. Using email marketing to increase customer loyalty through member rewards and promotions is a great way to get that buy-in.
  • The Double Opt-In – Confirmation opts in. Do you really want to risk annoying customers with this? Yes, you do. And a lot of the time, the customer is actually looking for this. For brand loyalists, it gives them peace of mind. It’s also a good way to ensure that you have accurate email addresses to ensure email deliverability. Yahoo.com may seem easy to spell, but Jack Hogan, CTO, LifeScript, found there are more than 500 ways to get that spelling wrong.
  • The Welcome Series – The Welcome Series is a great way to give the customer an overview of what to expect from the newsletter or mailing list they opted into. If your potential customers are opting in, it means they are looking for news about you – and that means higher clicks.
  • The Amazing Email Marketing Integration – Marketing in silos? Not so hot anymore. Integrating your email marketing efforts with social and across other channels brings about a much higher clickthrough rate. It’s all about cross-channel these days – that’s how the conversation’s taking place.

The continuing growth of integrated marketing in 2013

Here’s a list of what the movers and shakers in the online world are saying about integrated marketing. We’re particularly interested in this comment:

“In 2013 we will see social media teams working much closer with e-commerce teams, and ‘integrated digital marketing’ will take shape. The laggards will be email marketers who will still feel comfortable in their established metrics and existing silo’d processes.”

Since this blog is all about email marketing, you’d think we’d take issue with this comment. But we’re going to go out on a limb and agree – email marketers will lag… IF they continue marketing in silo. We’ve been advocating cross-channel marketing for a while and we still stand behind that. Email still drives the highest ROI, – it’s not even an issue for debate anymore. Adding social and mobile tools to your arsenal will only increase the chances of customer conversion.

7 Ways To Improve Your Email Deliverability 

We’ve often featured articles that talk about improving deliverability from a content perspective – this one differs in that it takes a slightly more technical view and lists 7 areas you should look at when it comes to improving the chances of email getting into your customer’s inbox.

Also have a look at the Top 5 Reasons Your Newsletter Will Go To Spam where the issues of cold IPS, unusual bursting, content, improperly setup infrastructure and incomplete list maintenance is covered in greater detail.

Yahoo sued for text spam

Yet another company finds itself in hot water for text spam. The Telephone Consumer Protection Act states that companies cannot use automated dialing systems without the consent of the consumers. Violations result in a $500 fine. Despite the heavy focus on mobile marketing due to its explosive growth, it is an area where companies can easily cross the legal line, despite recent updates to the Act. The answer to avoiding all this legal trouble then, lies again in .

Gmail’s New Compose View Now Gives You The Ability To Add Labels And Stars 

Google’s constantly tweaking Gmail for improved usability. The new Compose Now view gives you the ability to add labels and stars to your email as you are writing it, saving time spent looking for the email and starring or labeling it only after it has been sent.

Learn more about improving your email deliverability and feedback loops in the Proven Tips for High Volume Sending webinar!

Proven Tips For High Volume Sending