Comment 1 for bug 266271

Can you be more specific?

I have tested both Mailman 2.1.5 and 2.1.6 and they accept a
host_name of the form [142.56.2.72] on the General Options
page with no problem.

Is your issue that you can't get General Options to accept a
numeric IP in square brackets, or that it is accepted, but
it gets 'changed' somewhere else. Please clarify, and if the
latter, please be specific about where you observe the 'change'.