Docker Apps for Warming Up SMTP IP Address

One of the difficulties in setting up a new mail server is ensuring IP address reputation. Sometimes, I need a bunch of IP address to be setting up as SMTP gateway and due to its poor reputation history, our mails ended on spam or junk folder on the destination account.

Building a reputable public IP address need simultaneous improvement. Take care incoming and outgoing email, enforce security filter and sending a low volume of emails and then gradually increasing it until reach the desired sending level. The process itself is known as Warming up IP and I’m thinking to build a Docker Apps to achieve this goal.

Here is my initial idea :

1. Docker Images based on Ubuntu 18.04 or any new LTS version with plain postfix as mail server app
2. Has blacklist checking capabilities against major blacklist provider
3. It can send a number of emails periodically and then increasing sending level gradually, something like send 10 email/hour in day 1, 15 email/hour in day 2 and so on
4. Equipped with DKIM/DomainKeys, SPF and DMARC. It will need additional step regarding DNS records but I can manage it manually

That’s all. I’ll be start working on Dockerfile and update the progress on this blog.