We send about 600,000 transactional emails a month through SendGrid. Some customers mark a receipt as spam and then miss later critical emails because they are suppressed. Our tools cannot add SendGrid's override headers.
Would self-hosting Postal on a VPS help, or are we just trading one delivery problem for another?
Postal can send the mail, but it won't make complaints or bounces disappear. You'd take responsibility for processing them and deciding when to stop sending. Keep sending to addresses that reject mail or complain and your IP and domain reputation can suffer.
A VPS IP adds another unknown. Before moving production traffic, check whether the provider permits outbound mail and what reputation the assigned IP has. Set up SPF and DKIM, check DMARC, and plan a gradual rollout rather than switching all 600,000 messages at once.
I'd start with the suppression workflow rather than the mail server. Can your support team query why an address is suppressed and explain it to the customer? A portal message could help too, with a way for the customer to request restoration where appropriate.
Check whether SendGrid offers a suitable API or account-level option for your particular suppression type. Don't assume every suppression can or should be overridden the same way. A spam complaint, a hard bounce, and an unsubscribe need different handling.
understated+toolbox:
The header limitation is what prompted the question, so an API or account-level route would be worth checking.
Try another managed sender before signing up to operate mail infrastructure. Providers such as AWS SES, Mailgun, and Mandrill may offer different suppression controls, but check their policies and APIs against your exact workflow first. Switching providers alone may not remove the problem.
Be careful with the idea of simply overriding every complaint. Transactional content doesn't automatically settle every question about consent, opt-outs, or provider rules. The treatment can depend on the message and jurisdiction, so get advice for your use case before building a bypass.
For the truly critical stuff, consider a second channel as well. Email can be delayed, filtered, or rejected even without a suppression list. An in-app notice or SMS might give customers another way to see the message, depending on what the notification is and what channels they have available.
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u19+adc_73:
Also make sure someone will be watching delivery failures and complaint signals after the rollout. Getting the server running is only part of the job.