If you are sending email from a new or “cold” IP address, ISPs have no means of determining your sender reputation. Since this reputation determines whether or not your emails are delivered to your recipients’ inboxes, it is vital to immediately begin establishing a good reputation.
Remember that it is much easier to establish a positive reputation as a new sender, than it is to repair an existing reputation.
If you are sending a very low volume of email (less than 10,000 emails/month), ISPs will probably not pay much attention to your sending habits. However, if you are sending higher volumes, the IP warmup process plays a much more significant role in establishing your reputation.
We recommend that all users warm up new IP addresses regardless of the amount of email they send.
Your IP address’s history is another important determinant for ISP spam filters. Here are a few additional tools you can use to monitor the reputation of any IP address: