+2  A: 

After reading a message, you could unset the seen flag. See also the imap implementation of the setFlags method. Api documentation

WardB
Would this take into account messages that were already read?
Bob Cavezza
my thought exactly ... just reset the read flag on the message after you have read it with php ... should work with IMAP
ChrisR
Yes. You would actually want to read messages without touching the flags. Can't seem to find a way to do that in the ZF documentation.
WardB
@ChrisRamakers @WardB - you guys wouldn't happen to be able to point me in the direction of documentation for flag resetting, would you?
Bob Cavezza
A: 

When reading mails with the IMAP Storage in Zend Framework you have access to a method called setFlags in Zend_Mail_Storage_Imap

I don't think it's documented in the ZF manual but you might want to look into the API docs (see link above) to set the status/flag on a message.

ChrisR