IP warming is the practice of gradually increasing the volume of mail sent via a dedicated IP address according to a predetermined schedule. This gradual process helps to establish a reputation with ISPs (Internet Service Providers) as a legitimate email sender.
When an ISP observes email suddenly coming from a new or “cold” (i.e. recently dormant) IP address, they will take notice and immediately begin evaluating the traffic coming from that IP. Since ISPs treat email volume as a key determining factor when detecting spam, it is best to begin sending a low to moderate volume (e.g. up to 1 million emails/month), eventually working your way up to larger volumes (e.g. over 1 million emails/month). This gives the receiving email providers a chance to closely observe your sending habits and the way your recipients treat your email.
It should be noted that taking this gradual, ramping approach does not guarantee a perfect sending reputation. It is still important to follow sending best practices. Remember to always
- Send content that your users wish to receive
- Practice proper contact list hygiene
- Send email at a consistent and appropriate frequency