Related Posts

ESPs and deliverability

There’s an ongoing discussion, one I normally avoid, regarding how much impact an ESP has on deliverability. Overall, my opinion is that as long as you have a half way decent ESP they have no impact on deliverability. Then I started writing an email and realised that my thoughts are more complex than that.

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New Deliverability Resource

The nice folks over at Postmark shared a new deliverability resource last week. The SMTP Field Manual. This is a collection of SMTP responses they’ve seen in the wild. This is a useful resource. They’re also collecting responses from other senders, meaning we can crowdsource a useful resource for email deliverability folks.

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Undelivered mail without a bounce

A few weeks ago I wrote a blog post focusing on one small part of bounce handling. Today I want to talk about delivery failures that aren’t bounces. This is really the biggest issue for companies who have written their own bulk sending servers. Modern bulk MTA appliances and ESPs correctly handle these types of bounces. However, when you’re troubleshooting it’s important to know that sometimes there won’t be a SMTP level bounce.

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