Postmark vs SendGrid: What Each One Tells You About Delivery

If your organization sends through both Postmark and SendGrid — one for transactional, one for bulk, or just mid-migration — you've probably noticed the two don't describe delivery the same way. Same email program, two vocabularies, two dashboards. This is a short guide to what each provider actually surfaces, and where the overlap is thinner than it looks.

Both give you the core delivery events

Delivered, bounced, deferred, complained (spam report), opened, clicked. Both providers emit these as webhook events, and for the day-to-day question — "is mail getting through, and is anyone marking it as spam" — either one answers it. If all you need is a bounce rate and a complaint rate per provider, both are adequate on their own.

Where they diverge

Bounce classification. Postmark leans hard into typed bounce reasons — hard bounce, soft bounce, spam notification, transient, and a couple dozen more specific codes. SendGrid's bounce data is present but coarser by default; you often get the SMTP response string and have to classify it yourself. If your list-hygiene process keys off why something bounced, that difference matters.

Suppression handling. Both maintain suppression lists (addresses they'll refuse to send to after a hard bounce or complaint). How you read and manage those lists differs enough that a person watching one provider's suppressions has to relearn the model for the other.

Message-level tracing. Postmark keeps individual message activity queryable for a retention window — you can pull up one recipient and see exactly what happened to their last message. SendGrid's equivalent (Email Activity) is available but gated by plan and has its own retention rules.

The problem isn't any single provider's data — it's that it's split

Each dashboard is fine in isolation. The friction shows up when "our bounce rate is trending up" has two separate answers depending on which tab you're looking at, and nobody's comparing them on the same axis. A migration between the two is the worst version of this: for weeks, half your volume is described one way and half another.

What InsightForge does with this

InsightForge ingests delivery and engagement events from Postmark, Azure Communication Services, and SendGrid into one view, so bounce and complaint trends for the same customer base sit on one chart instead of three. None of your data leaves your Azure tenant.

Worth being precise about the SendGrid integration specifically: it covers delivery and engagement events — sends, bounces, opens, clicks, complaints. It does not sync SendGrid's suppression list, manage sending domains, or provide a Received:-header analysis like Header Detective does for Postmark messages. If your reason for running InsightForge is unified bounce and complaint visibility across providers, SendGrid is fully in scope. If you need SendGrid-specific domain or suppression management, that still lives in SendGrid's own console.