Another option is to write the forum name at the end, since the current email clients have pretty rule systems and filters to tag, colorize and move emails... there is no need of reading the forum topic by the human. So, instead of something like...
[forum-name-which-is-too-large] Forum-subject X
[forum-name-which-is-too-large] Forum-subject Y
[forum-name-which-is-too-large] Forum-subject Z
[forum-name-which-is-too-large] Forum-subject A
we could see:
Forum-subject X [forum-name-which-is-too-large]
Forum-subject Y [forum-name-which-is-too-large]
Forum-subject Z [forum-name-which-is-too-large]
Forum-subject A [forum-name-which-is-too-large]
so...
Re: Forum-subject X [forum-name-which-is-too-large]
Re: Forum-subject Y [forum-name-which-is-too-large]
Re: Forum-subject Z [forum-name-which-is-too-large]
Re: Forum-subject A [forum-name-which-is-too-large]
