Okay the
imap_open() [function.imap-open]: Couldn't open stream
Error is most commonly due to the wrong connection type being chosen. If you get this error, try changing the type to one of the other 6 and rerunning the cron manually.
I suggest ONLY setting the settings up for one forum til you know what the settings need to be to work for your server
Otherwise, you could have one forum set wrong, and another set write, yet be getting frustrated by the error message that isn't going away
Also!!!
NOTE! You must have a separate mailbox for each forum you wish to be enabled! Just like yahoo groups each have a different email address
The reason for this is to significantly increase the end user's ability to create a new thread by just sending an email with whatever title and message they want to the mailbox, which will then be grabbed by the cron and posted as a new thread