Just as an FYI, I just moved one of my mail servers from an old debian
squeeze (php5.3) to debian Jessie (php5.6). I read all the notes on the
php5.4 upgrade and pulled a fresh copy from svn and ran the
squirrelmail-php_5.4-htmlspecialchars_update.diff patch. Other than
that it was a straight copy from one server to the other.
So far the only glitch I have run into is that the preview_pane plugin
causes the reply/forward/etc buttons to not show up when you click to
view the message unless it is turned on. IE if the option is turned
off, you cannot reply when viewing a message. If it is turned on, the
buttons do show up in the preview pane.
Sorry I didn't do more significant testing or investigating, but the
problem is resolved by disabling the plugin, so I am calling it good for
now because I need to move on to some other things. Just thought I
would report it....
867-334-7117 / 867-633-3760