Basically, I'm unable to upgrade to CSSU 16.5. It seems the root of my problem is that in /var/lib/dpkg/status modest-home-applet is listed as deinstall ok config-files. (It's causing a broken package message in apt-get.) To the best of my knowledge, if that were the case I'd have no email! So, is it OK for me to manually edit the status to install ok installed?

The package that this is holding back is mp-fremantle-community-pr. If I try to install that individually, it's at that point I get errors relating to modest.

No, that is only the mail widget on the desktop. The mail program itself (modest) is not affected.

The applet was deinstalled during the CSSU update for me as well. I reinstalled it afterwards by hand:

apt-get install modest-home-applet (as root of course)

Not the first time that happend. Dunno what's causing it.

Tried that but I'm getting a message saying modest-home-applet is missing, basically. I've checked that the required repo is enabled & have done an apt-cache search for home-applet with turns up others like calendar-home-applet but no modest home applet. Any ideas?

Sorted it! I fired up HAM, disabled the repos that modest home applet was likely to be in then re-enabled them after an update. After a further update, I could then install modest-home-applet and the upgrade ran through fine. CSSU 16.5 now being reported in settings.