ossec/ossec-hids — pull request #216 by Nukama (2014-05-28 13:04:05+00:00)
Title: Allow + in valid_email_addresses in installer.sh

man grep:
In basic regular expressions the metacharacters ?, +, {,	|, (,	and ) lose their special meaning;
instead use the backslashed versions \?, \+, \{, \|, \(, and \).