What is this?
This is a missing PEAR module. You can try installing it by using the PEAR command line interface, like this:
If that doesn't work, download the tarball from here and copy the Socket.php file into your PEAR library directory (usually /usr/local/lib/php/) into the Net subdirectory.
Most probably, this is an IMAP/SSL problem.
First, try using the IMAP testing page. Open the page apps/mail/test-ima.php in your browser (so, if JAWmail is installed in http://server.lan/jawmail/, load http://server.lan/jawmail/apps/mail/test-imap.php).
Now, enter your IMAP username and password and enter the hostname of your IMAP server. In case that the connection will fail, try choosing another IMAP protocol. Most probably, imap/notls will work. If it does, reinstall JAWmail and select the appropriate IMAP protocol during installation.
The most common problem is that some system locale files are missing. Here is the long method to identify this problem:
In case that this doesn't help...
Oh, there is a lot of work where you can help!