Deleted Messages using ActiveSync and IMAP

Hi,

we have Zimbra 8.0.3 and Zextras 1.8.4 on Ubuntu 12.04 in a trail version installed.
everything works well but we have a issue with activesync and IMAP.
Whenever I delete a messages either in iMail via IMAP or in the Zimbra web interface,
but they will still show up on my iPhone in the inbox.

is this a known issue?

thanks in advance,
velvet