Is there any limitation on the size of a mail?

Hello,

Sorry for this noisy mail.  If there is more appropriate address to
send to, please tell me.

I sent one mail about load-distributed checkpoint three times on the
following dates as I couldn't see the mail on the ML:

2006/12/16 17:53
2006/12/18 9:07
2006/12/18 12:10

But none has appeared on pgsql-hackers ML yet.  What's wrong?
One thing I worry about is the size.  The size of my mail is 42KB.  It
has only text and no attachment.  Is there any limitation on size?

I'm sending this as a test too.