Resolving: ERROR : Connection dropped by imap-server. Query: CAPABILITY

In /var/log/maillog you may see something like:

Sep  7 22:32:23 host dovecot: chdir(/home/someuser) failed with uid 506: Permission denied

In that case make the directory owned by them:

chown -R someuser:someuser ~someuser

I installed squirrel mail. Now: where is it?

On RH based distros the RPM package sets up an Apache Alias so that squirrel mail will be at http://yourip/webmail/index.php.

On other distros (e.g. on Debian Sarge) you can add the Alias yourself via a line like this in the Apache conf file (then restart apache):

Alias /webmail/ "/usr/share/squirrelmail/"