Can asmBB be used in place of a mailing list? I'd like to set this up but also replace an existing mailing list, so current users may expect to be able to receive whole posts/replies via email and to be able to post by email.
Is this something that already exists for asmBB? If not how much would would it be to set it up?
Well, the forums are kind of replacement for the mailing lists, but they work in totally different way.
AsmBB has an interface to a smtp server and can send emails, but it tries to use it to the least possible extent, because the forums in addition to their other advantages are also a good way to prevent spam, simply because the email addresses are not public.
But AsmBB has no email client, so it can't check the received emails and post them automatically in the forum.
So, while it is not a big problem to send every post to a list of emails, personally I am not very sure it is a good idea at all.
In addition, you will not be able to migrate your users automatically and they must register themselves. Once registered they can use the forum simply as a web forum.
So a hybrid between mailing list and web forum is not the direction where AsmBB will be developed.
What is planned to be implemented is a RSS feed notifications for the users. Maybe it worth to be implemented an email notifications as well.
Sometime in the future, I am planning to make a desktop client for the forum, but this is a long term plans.
P.S. BTW, while using AsmBB in "mailing list" mode is not possible and not worth to be implemented, it is probably possible the old mailing list archive to be migrated to the AsmBB database. This way, the users will have all the old emails in one place.