tail_n_mail (sometimes abbreviated TNM or tnm) is a Perl script for automatically detecting interesting items that appear in log files and mailing them out to interested parties. It is primarily aimed at Postgres log files but can be used for any files.
It was developed at End Point Corporation by Greg Sabino Mullane.
The latest version, 2.4.0, can be downloaded here:
Full documentation can be found at https://bucardo.org/tail_n_mail/