Fast-Tracking Email Deliverability: My Experience with AI-Powered Warm-Up

This story started when I connected a fresh domain to Fastmail. I wasn’t expecting any issues at first — after all, it was just email, right? But things didn’t quite go as planned. Let me walk you through why I turned to AI for a solution.

Fastmail Email Setup: My Experience

I hooked up a brand-new domain to Fastmail, one I’d just bought from GoDaddy specifically for email purposes. About 20 minutes after the nameservers started resolving, I sent the first couple of test emails to make sure everything was working. The emails took 20 minutes to arrive. I was sending from Fastmail to Gmail and Protonmail. “Alright,” I thought, “let’s run the test again.” Sent another couple, and these took four hours to show up. The next two? They didn’t land until eight hours later. These were just basic emails — no attachments, just a few lines of filler text.

I went through all the settings, double-checked everything, and made sure the domain wasn’t blacklisted (using public databases). I meticulously went over the DNS settings, along with DMARC, DKIM, and SPF headers. Everything was fine. But when I checked the headers of the emails I had sent, they showed an X-Spam-Score of 30. That’s ridiculously high, especially for a brand-new email address and domain. And that turned out to be the clue.

Finally, I reached out to support, and they told me that all new domains undergo a 30-day quarantine and are automatically considered suspicious. Emails from these domains get scrutinized more intensely for spam. Over time, spam filters gradually start to trust you, performing fewer deep scans. As I was told, essentially, it should all smooth out after a month. A whole month before I get out of the gray zone.

Fixing Email Delays with AI

So, I asked ChatGPT to help me put together a precise, step-by-step warm-up plan for the email account. We went through all the details—how many emails I should send from this new address to my existing mailboxes, what kind of (fake) content to include, what to write in the subject lines, which words to avoid in the body of the email, how to gradually increase the frequency of sends, and when to just reply versus when to initiate new messages. We even covered how many emails to send, when to attach files, and from which addresses.

But it wasn’t just a simple checklist—I ended up with a fully fleshed-out strategy, complete with a detailed timeline down to the hour for each step. At specific times, I’d copy the content from the plan (ChatGPT had even invented a whole backstory to maintain the context of the email thread), follow the instructions on what to include in the subject line, format the body, and send it to one of my other addresses. The next instruction would be something like, “Reply to this email after XX minutes with the following text,” which I would do exactly at the scheduled time. Then came the next step, telling me to send an email from a third address, and so on.

Honestly, I’m almost certain I could have automated this entirely and removed myself from the equation. But it didn’t take much of my time—I was busy with other things, and when a reminder popped up, I’d just copy the text, hit send, and move on. Plus, whenever I received an email, I’d check its headers (to see where the delays happened and what the spam score was) and have ChatGPT analyze the results. This helped me make any adjustments to the plan as needed.

After just a few days of following the instructions, my emails started arriving in 22 seconds, and the X-Spam-Score dropped to 4. Not perfect, but acceptable. So yeah, I didn’t have to wait 30 days. Warmed up the mailbox with ChatGPT’s help.

TIL: Avoiding Early Email Setup Pitfalls

Well, here’s something I recently learned from support:

One other thing worth mentioning is that empty “test” messages are more likely to trigger spam filters, so I recommend you avoid sending any sort of empty or one-word messages.

In fact, my first few emails were exactly like that, so I unintentionally shot myself in the foot. Let this be a small reminder — when setting up a new mailbox, especially with Fastmail, try to avoid sending these kinds of emails early on.