Mailaza.com – Inspect SMTP

You’re not inspecting the SMTP protocol itself. You’d have to sniff the network traffic between the two points in question.

This is an ephemeral catch-all mailbox that lets you inspect all the headers on mail messages that are received, and once you leave the page, those messages are gone.

Not really sure how useful that is for debugging mail messages. In the 30 plus years I’ve been doing mail servers and debugging mail problems, I’ve always wanted to keep examples of problem messages so that I can refer to them later.

Great tool!