slackbuilds/network/dovecot

This script builds dovecot with support for SSL. As such, you must have
openssl installed - openssl-solibs is not enough in itself to meet this
requirement.  Additionally, dovecot will be compiled with POP3 support.

You should create a dovecot user to run the login processes on your server. 
Something like this should work:
[root@host] # groupadd -g 202 dovecot
[root@host] # useradd -d /dev/null -s /bin/false -u 202 -g 202 dovecot

See the documentation in /usr/doc/dovecot-2.2.6/ to get started.