In order to resolve the duplicate trash/deleted messages and sent/sent messages folders on my iPhone and Mac I changed Squirrelmail options so that my "sent" messages went to "Sent Messages" and deleted items went to "Deleted Messages".
On my Mac and my iPhone and Squirrelmail everything is syncing up ok.
I was even able to delete the "Sent" folder under INBOX on Squirrelmail (so it doesn't show up on my Mac or iPhone). But for some reason I can't delete the "Trash" folder, so it shows up as a useless folder/duplicate on my Mac and iPhone.
If I use the INBOX.Trash folder as my deleted mail, I end up with another trash folder on my Mac and iPhone, so that's not a great solution.
Any help here?