NB! The fixes, described below, apply only to e-mail client shipped with PR1 2. PR1.3 already has all those problems solved.

I did put together a custom version of modest, to fix some bugs that PR1.2 introduced: send/receive and email notifications not working with POP3 accounts and messages deleted from server regardless of "Leave messages on server" setting.
Latter was fixed in git already, for former I had to come up with some patches. I did make some performance improvements too, to reduce the time it takes to check for messages: original version checked 3 times in a row when send/receive button was pressed in headers window Now it does it only once.

The patched version, which is in attachment, is based on http://gitorious.org/modest/modest modest-3.4 branch. To install, copy this file to N900, become root and unpack it:
This will overwrite /usr/bin/modest.launch and /usr/lib/camel-lite-1.2/camel-providers/libcamelpop3.so. Reboot your phone.

To uninstall, just reinstall modest and libcamelpop3 from PR1.2:
I have tested it with my POP3 and gmail accounts and it seems to be working fine, but I cannot give any guarantees, use at your own risk.

Thanks for your efforts! I use 3 pop accounts heavily and Modest could use some polishing.

The 'leave messages on server' (not!) bug was beginning to drive me buggy. I'll have to use it more before a can say much about performance differences. But it installed no problem. No errors, trashed settings or anything like that. Did a couple of test messages, seems good so far.

Thanks again!

Wow...great to see that you debugged this. It would be great if this were a proper package though, as this method is a bit of a pain.

Do you have your fixed code somewhere?

I had it in .deb-s, but this caused problems. modest and libtinymail-* packages are part of PR1.2, when I updated them with dpkg, I could not install anything that depended on PR1.2 anymore. I'm not very familiar with debian packaging, maybe it's somehow possible to update PR packages without serious sideeffects. I settled on tar.gz, to avoid any conflicts with apt-get and app manager.

Even the tar.gz method could cause some problems. You might have problems future upgrades anyway, because you never really know what newer packages might do.

I'd rather take my chances with packages. Would you mind attaching the ones you made? Hell, the worst that could happen is that it breaks Modest, which doesn't work anyway, so I figure I've got nothing to lose Besides, reflashing doesn't really scare me...

Ok, I uploaded debian packages to another server, libtinymail-camel is too large for an attachment:

libtinymail-camel-1.0-0_1.1.91-baxyp.1_armel.deb
modest_3.4.2-baxyp.1_armel.deb

Anyway, I do not recommend those as these broke my ability to apt-get another packages later. libtinymail-camel contains other camel libs in addition to libcamelpop3 and this may break something. The tar.gz method should be fine until PR1.3 and considering how long it took for 1.2, I think there is time

Agreed. I rarely install from tarballs. I'd much rather have a package manager be aware of what's installed and so be able to keep track of conflicts and dependencies. But since you already know the .debs cause trouble, this might be one of those rare instances where it's better to keep the package manager unaware.

Anyway, the modded version is working well for me so far. Mail is correctly left on the server, modest isn't sometimes grinding away for 5 min to do a mail pass and overall speed might be better.

I can say it seems to work. I gave it what I'm starting to call the "nightstand test," where I take it to bed with me, leaving it on the nightstand next to the bed. When I woke up this morning, it was still working, so I think it's safe to say that baxyp's fixes have resolved the bug.

@baxyp: have you considered submitting a patch to the Modest/tinymail devs upstream?

When I have time, I'll update bugzilla and explain what was causing POP3 mailboxes not to refresh. My patch is more like a hack, maybe modest/tinymail devs will implement it properly.

excellent work. just installed and it works perfectly.