Comment 1 for bug 266326

Both bin/newlist and the Cgi create script invoke the exact
same Mailman/MTA/Postfix.py module to update the aliases.
The only difference is the user/group under which it runs.
Thus, this is most likely a problem with the 'mailman' group
not having write permission on data/aliases*. Both
data/aliases and data/aliases.db should be group owned by
the 'mailman' group and be group writable.

This may be FAQ 6.9 -
http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq06.009.htp

If this is not a permissions issue, please post the
traceback from the "bug" from Mailman's error log.

Note that the "#CREATED:" line in the aliases file is a
comment and is intended to be there.