Paul Dean wrote this on 19 December 2024. Easy Eatery sends booking confirmations, receipts, and gift vouchers for restaurants. Those messages are the product.
Hotmail, Live, and Outlook started rejecting some of them. Less than 2% of mail failed. A gift voucher that never arrives is still a refund. He treated that rate as unacceptable.
If you are looking at the same route, start with the SendGrid → Postmark playbook. Postmark publishes a SendGrid migration guide. Paul’s post is the incident, not the DNS checklist.
Shared IPs, and a second time
The IPs SendGrid used for their mail had landed on block lists. Easy Eatery shares those IPs with other SendGrid customers. One noisy neighbor is enough.
This was not the first incident. An earlier round was fixed by working with SendGrid to unblock the addresses. This time the mailbox providers refused. They said quality across the pool had not improved.
Paul also says he personally received phishing from other SendGrid users that week. That is his inbox, not a block-list dump.
SendGrid will sell a dedicated IP. He does not say they bought one. The post jumps to a new vendor.
Forty-eight hours, little plumbing
They picked Postmark because every account is manually reviewed. He wanted a pool that is harder to join.
From first failed-mail investigation to Postmark sending in production was under 48 hours. Approval was fast. He calls the integration simple and the docs clear. He does not name the API, the SMTP host, the DKIM records, or a template rewrite.
Postmark’s own guide is the missing half. Create a server, verify the domain, move suppressions, rewrite the API or SMTP call, then watch a known receipt. Paul never walks those steps. I am not inventing them for Easy Eatery.
He had been on SendGrid for nearly two years with no serious trouble before this. He says he would still recommend SendGrid if the block lists had not shown up. Early Postmark mail was arriving. He calls it early days.
No bounce chart. No before-and-after inbox rate. No dual-run window. The gain he claims is reliable delivery after the Hotmail rejects.
What I would copy
Watch Hotmail, Live, and Outlook as their own cohort. Paul’s fail rate was small and still enough to move. A global “delivered” number will hide that pool.
If you have already asked SendGrid to unblock a shared IP once, decide the next incident in writing. Dedicated IP, or a vendor that reviews accounts. He chose the second.
Do not treat “we integrated quickly” as a domain move. Copy SPF, DKIM, and the suppression list from the Postmark SendGrid guide even if the app change is one SMTP password.
Keep SendGrid able to send until a known Outlook address receives a real voucher or booking mail from Postmark. Paul does not describe that check. I would still run it.
The SendGrid → Postmark playbook is the domain and webhook list. Use Paul’s post for the shared-IP trigger, and remember he skipped the DNS.