Tagmx

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...

Microsoft changes

There’s been quite a bit of breakage and delivery failure to various Microsoft domains this month. It started with them changing the MX for hotmail.co.uk, then the MX for hotmail.fr… and both these things seem to have broken mail. I also saw a report this morning that some of the new MXs have TLS certificates that don’t match the hostnames. What’s going on? Historically...

The Internet is hard.

There are so many things that need to happen to make the Internet work. DNS entries need to be right. MXs need to be set up. Web servers need to be configured. And, let’s be honest, anyone who has ever run their own services on the Internet has flubbed a configuration. We don’t think about it, because most of the time the configurations are handled by scripts and they do things right...

The long tail of domains

I frequently get clients telling me that they have about 15 (20, 30) major domains on their list, and then a long tail of domains with only a couple of recipients. If you sort simply by the left hand side of the @, that’s true. When you’re sending email, it’s not just the domain in the email address that is important. Of equal importance is the MX. The MX is what actually...

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