Troubleshooting path MTU problems
Originally published at tolaris.com. You can comment here or there.
Not long ago we started having very unusual issues our email servers. Mail would be inexplicably held for delivery, bounce back, or fail to send for hours and then send without issue later. Some users couldn’t fetch email by POP until they restarted their mail client. We investigated the mail software, but weeks of investigation turned up nothing.
Around the same time, we also experienced intermittent problems logging in to MSN Messenger, and some users complained of issues accessing certain web pages, including a lot of HTTPS links. I began to suspect these were related.
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