fetchmail choked on a piece of mail

[Joel Hammer]

My incoming mail goes to various mail servers on the internet, and I run
fetchmail to get them from various POP servers.

Today, for the first time in memory, when  fetchmail tried getting my mail,
a particular piece of mail kept freezing during the download and fetchmail
would finally stop, giving  an error message of some sort or another.
I had to go onto the server with telnet and delete that piece of mail,
then, all went well.

So, the question: What kind of mail would freeze the download and kill
fetchmail?

Joel