I've seen several reports on this list of timeout errors with large emails. I'm getting a timeout -- or at least some kind of 'hang' -- every time I send an email. Client-side is running Debian sid, Firefox 1.5.0.1, although I also got the same result with Opera 8.5.
The email actually goes through fine, but the "Loading..." translucent box never disappears, nor does the browser ever reload to the message page after sending.
Adam Rosi-Kessel http://adam.rosi-kessel.org