It's been two months since I am running a mail server. I worked on a beautiful UI like SendGrid and MailGun for more than six months. I plan to start a transactional email service.
I bought a range and rented another /24 range because I didn't want to have a bad neighbour on the subnet. I even got my own ASN because jerks like UCEProtect often put big ISPs on a blacklist at the ASN level.
Of course, I have got a decent experience with this. I wrote my own SMTP server, email routing, and other things such as bounce and suppression handling. In a sense, everything is fine. RDNS, DKIM, DMARC, and SPF.
I know that IP needs to warm up, so that's where I started. I paid for a few services to help me warm up, and it took me about two months to do so. Okay so far. The email was delivered 100% of the time to Gmail, but not at all to Yahoo and Outlook. The delivery rate to these two companies started to get better around last week, though. Some IP addresses started getting a 100% delivery rate.
Then, I started testing my service on one of my websites. Of course, 100% transactional emails with account confirmation links ONLY. It was working great. Nearly 2,000 emails, 3,000+ opens and about 2,500 clicks daily on an average.
I've also subscribed to Glock Apps and MXToolbox to measure my email deliverability and monitor IPs.
Just today, I received an email with all half of my active IP addresses and sending/tracking domain blacklisted by Spamhaus. They categorize it under "spam domain", but I looked through my server logs (yes, everything is logged) and found no evidence of spam. Only transactional and warmup emails sent. I opened a ticket with Spamhaus and refuse to unblock my IP addresses and domains.
I spent 6 months and $20,000+ working on this, only to be butchered by Spamhaus. I want to kill myself. How can Spamhaus be the police, judge and the executioner?
This has been going on for at least a decade, I'm not really sure how you can spend half a year and 20k doing something without stumbling upon countless examples of the same behaviour from Spamhaus & Co.
Sorry that this happened to you.
I was really confident that I could maintain a good, positive IP reputation which I did. Until I got banned randomly.
The software that I built has features to combat end-user spam:
At my previous workplace we were hosting separate email servers for each customer on their own, private application instance. One of our clients was a national postal service from Europe, their corporate side forced them to use the highest notification frequency they could configure in our software upon all users.
After some time, their IT started reporting our IP address to various spam lists and they even sent abuse report to AWS. It was fun...
At least for me, I always made sure to never touch anything email-related, that's how you become the "email guy".