If you like very busy mailing lists, you can try subscribing to London.pm's mailing list, or to the Perl Beginners mailing list, which despite the name gets a fair share of medium level questions.
For a much more sedate mailing list, you can try Israel.pm's mailing list, which currently gets only a few mails per week.

As someone else pointed out, there are many groups listed on pm.org. However not all are active (in fact a good share are not active at all) and from those that are, not all are in English (both London.pm and Israel.pm are English only).
Maybe other people will now give links to other active, English langauge mailing lists of other user groups. It's up to you to decide which you want to subscribe to. However I don't think there is lack of choice...