major.io words of wisdom from a systems engineer

Dovecot: libsepol.so.1: failed to map segment from shared object: Cannot allocate memory

You may catch this error when you attempt to start dovecot on a Red Hat Enterprise Linux 5.1 system with the 64-bit architecture:

dovecot: imap-login: imap-login: error while loading shared libraries: libsepol.so.1: failed to map segment from shared object: Cannot allocate memory
dovecot: pop3-login: pop3-login: error while loading shared libraries: libsepol.so.1: failed to map segment from shared object: Cannot allocate memory

If you start dovecot, the main dovecot daemon will run with one auth child process, but there will be no POP/IMAP processes started. To fix the issue, open the /etc/dovecot.conf and adjust the following directive:

login_process_size = 64

Restart dovecot after making the change:

# /etc/init.d/dovecot restart

This was tested on RHEL 5.1 x86_64.