Ok, you can have squirrelmail
auto-refresh your folder list which will:
1) Let you know when you have new email and,
2) Keep you from being logged out, especially when typing a long email.
Here's how:

First, log into squirrelmail, like I have above. Then click on
the "Options" link near the top of the page.

Next, click on "Folder Preferences"

You should see where the "Auto Refresh Folder List" is defaulted to
"Never" -- change that to something else. I suggest 5 minutes, as
anything smaller tends to be annoying.

Then, click on "Submit" at the bottom of the page. That's It!!
(You may have to log out of squirrelmail to have it take effect
though...)
-Shawn