As the other gentleman pointed out, the exiqgrep program is just a perl script. It takes the raw value passed to the -r function (recipient) and uses it in a pattern match. The pattern match is a simple $rcpt =~ /$opt{r}/
perl test, the default match, since it's not specified, is case sensitive.
As with all things perl, TIMTOWTDI (There Is More Than One Way To Do It). Since the function above does not strip or sanitize the value passed to -r, you can simply embed an ignore case modifier in the regex. See perldoc perlre
for more details about how the (?MODIFIERS:...)
sequence works.
Here is an example where I show that a mixed case search doesn't find the domain I'm looking for, but by using an inline flag modifier as part of the search term, it finds it.
OVZ-CentOS58[root@ivwm51 ~]# exiqgrep -r 'crazyivan@yahoo.com'
26h 4.0K 1VGRud-0001sm-P1 <> *** frozen ***
crazyivan@yahoo.com
OVZ-CentOS58[root@ivwm51 ~]# exiqgrep -r 'crazYivAn@yahOo.com'
OVZ-CentOS58[root@ivwm51 ~]# exiqgrep -r '(?i:crazYivAn@yahOo.com)'
26h 4.0K 1VGRud-0001sm-P1 <> *** frozen ***
crazyivan@yahoo.com
Your search will be similar, something like:
(?i:@thedomainyouseek.com)