On 29 December 2020, jfx wrote about transactional email at SteamLevels. He says Postmark did not ask for the post. The path is Mailgun, then SendGrid, then Postmark. Skip the middle and you miss why a dedicated IP was the wrong next purchase.
SteamLevels sends two kinds of mail. A verification message, and a non-promotional note about the account, such as a support case. A user might see two emails ever. If the verification never arrives, the person cannot buy.
Volume was about 5,000 emails a month. When delivery broke, the first idea was a dedicated IP, so a noisy neighbor could not wreck the reputation. At that volume the IP never builds a reputation of its own. They kept looking for a vendor with clean shared IPs. He points at a Postmark article for the reputation background. The article is his recommendation, not a number from SteamLevels.
Mailgun, then SendGrid
Mailgun came first. Yahoo and AOL blocked it, so customers on those hosts never got the verification mail, and SteamLevels lost them. He notes that Mailgun had published advice about Yahoo and AOL, and that the advice did not help, because SteamLevels barely mailed those providers and was still blocked.
SendGrid was the famous next stop. Gmail and Outlook started working. About 93% of mail was delivered. The rest died because mailbox providers were blocking the shared SendGrid IPs over other customers’ spam.
He wrote to a German postmaster. The reply said the provider had placed them in a pool that regularly sends spam to that host’s customers and to its spamtrap addresses. SendGrid support would not move the account to another shared pool by hand. They said a manual move looks like snowshoe spamming. The offer was a dedicated IP at an extra $75 a month. Support also said they would normally not recommend a dedicated IP for this volume, and that it was still the most decisive fix. The other suggestion was to ask each postmaster for a whitelist. He left.
Postmark
Postmark made him fill in a form about why he was sending, and a person approved the account quickly. That review is how they keep the service limited to transactional mail. He praises support, including an offer to talk when you sign up, a weekly deliverability digest, and a free DMARC report summary.
Postmark’s dedicated IP, in the post, is an extra $50 per IP per month, with warmup. He describes the product. He does not say SteamLevels bought one. The result he reports is on the shared service.
Over three months and about 12,000 emails, 7 messages were flagged as spam, all at one Russian host. The bounce rate was 1.8%, mostly missing mailboxes from typos, or mailboxes over quota.
The $75 and $50 figures are what the December 2020 post says those vendors charged then. Read current pricing if you are comparing bills.
He mentions Amazon SES for people already on AWS, and Mailchimp for bulk mail. SteamLevels did not move to either. He would not recommend Mailgun or SendGrid for this job. He leaves open the idea of SendGrid for bulk, with a warning to watch delivery rate.
What I would copy
Write the monthly volume down before anyone sells you a dedicated IP. At about 5,000 messages, both SendGrid’s own support and his earlier attempt said the dedicated address was a weak fit. Postmark’s shared pool is what produced the 7 spam flags.
Ask the postmaster, or read the bounce, before you switch vendors a second time. The German reply named the pool. That is a different bug from a bad template.
Expect a manual review at Postmark, and budget the days. He was approved quickly. The Mailgun → Postmark and SendGrid → Postmark playbooks cover domains, sender identities, and the period when both vendors can still send. His post is the deliverability story. It does not list DNS records. Use the playbook for the cutover, and keep Mailgun or SendGrid from sending after Postmark is approved, or you are back on the pool you just escaped.