ISP’s have made it known that the warm-up process is a key factor in building a good email reputation. Every time you have a new sending domain/IP combination, you should go through a warm-up process in order to introduce your new combination to each ISP. This process helps build a solid reputation that will warrant your ability to send thousands, millions or even billions of emails a day through those ISPs to their customers.
In theory, this is a fairly easy process. A simple rule of thumb is to send 200 emails using the new sending domain/IP combination (SDIPC); then each day you can double the number of emails you sent the prior day. To improve your chances of a smooth warm-up process you should start sending to that new SDIPC with your best and most engaged customers. Within 2 weeks of doubling your sending, you should be able to send over 1.5 million messages a day through that SDIPC alone. In three weeks that number is an astounding 209 million messages a day! That amount is enough to support 99.9% of the legitimate senders of the world.
As discussed, with a great email reputation an IP address can handle millions of emails per hour, but you typically don’t want to send all your email through the same SDIPC, you should separate different types of sending through different SDIPCs. Different email types (categories) include password resets, newsletters, invoices, advertisements, personal daily updates like job listings and real estate listings. So even if a single IP address could support all of your sending, you may find it best to have multiple IP addresses.
Since most companies send several different email categories they typically find themselves warming up more than one SDIPC when moving to a new ESP vendor. Even if you are not moving to another ESP and you are simply adding a new stream of email, you will probably find yourself going through the SDIPC warm-up process sooner than later!
Check out part two of this series where I go over how to successfully implement the IP warm-up process.