Anyway, workaround: open the Today Pane (F11) and drag&drop the ICS file on there. Interface isn’t brilliant, but it works for now.

Enter the Lightning plugin for Thunderbird! With the previously mentioned DavMail, you can get your exchange calendar in Thunderbird. Which kind of beats Microsoft’s web interface – though not by much.

I also added a Google calendar via CalDav (which works directly with Lightning). Adding and deleting events is nicely synchronized :) Adding another (big) Google calendar, however, borked the overview (appointments no longer shown), though the list above the calendar still showed correct info.

DavMail to the rescue! It’s a piece of software that runs under Windows, Unix and OSX. What it does: it translates the secret Exchange-Outlook mail protocol into public protocols (POP, IMAP, SMTP, CalDav, LDAP, …).
And it works quite beautifully! Though you’ll need openjdk-7-jre for it to run.

Next, you can set up Thunderbird to get your Exchange mail via DavMail (username at the OU: XXX@pwo.ou.nl). And it works beautifully!

In related news: it seems you cannot stop Thunderbird from checking an account: if you’re online, it’s trying to check that account. Annoying if you have an old account to which you no longer have access (but have a local archived copy).

Except that sometimes, I right-click a message, but before I can select “move to”, the context menu is gone again. Annoying. Apparently, I’m not the only one.

Work-around: minimize the window and then restore the TB window again. The bug is still being hunted, as far as I can tell.

There is one button, no matter how hard I try, I cannot get to work.
You see, Thunderbird has a “Get mail” button. And I press it and press it, but do I get mail? nooooo….. ;-)

And just when I was ready to give up:

• sudo add-apt-repository ppa:ubuntu-mozilla-security/ppa
• sudo apt-get update && sudo apt-get install thunderbird

Apparently, there are all sorts of mozilla-related valid words (e.g., combinations with “security” and “release”) you can enter after “ppa:”. Some of them work , but don’t update your system. Such as the aforehinted mozilla-security-ppa and mozilla-release-ppa. This one does.

@Mozilla: is this really necessary? Just provide some sort of warning with pointer to the right location in the non-updating PPA’s, would you?

Somehow, the default locale it took was not my default locale (LC_ALL=C). So, to fix this minor annoyance, I changed the Thunderbird launcher to env LC_ALL=C thunderbird %u (where %u passes arguments — I just left it there).

In a nutshell, I set mailnews.default_sort_order to 22: sort by thread (where previously I tried 18 and other combinations of settings). Le duh. Now It Works(tm)

And yes, there’s a similar extension called Nostalgy, which hides this behind Esc+A. I tried it, and it worked… if I kept Esc pressed while pressing A. That’s awkward. This is way better :)

To do this:
I want descending (sort_order: 2), date-sorted (sort_type: 18), threaded (view_flags: 1) mails.
So change the relevant mailnews.default_* values to reflect that :)

The comment in full (to safeguard, and in case your settings don’t match mine):
(PS: Note that according to comment 102, further below, the linked comment had _type and _order swapped. That’s changed below.)

Prefs are named as follows; first three apply to Mail and RSS folders, the second three to Newsgroups.
  mailnews.default_sort_order
  mailnews.default_sort_type
  mailnews.default_view_flags
  mailnews.default_news_sort_order
  mailnews.default_news_sort_type
  mailnews.default_news_view_flags
In about:config  (Tools | Options | Advanced | General, Config Editor),
you can enter "news._def" to filter out all the prefs but these.

sort_type:
  byNone        17         byPriority    23      byLocation    29
  byDate        18 *       byStatus      24  	 byTags        30
  bySubject     19 *       bySize        25  	 byJunkStatus  31
  byAuthor      20 *       byFlagged     26 	 byAttachments 32
  byId          21 **      byUnread      27 	 byAccount     33
  byThread      22         byRecipient   28 	 byCustom      34
    * = commonly desired values
   ** = by Order Received (?)

sort_order:
  ascending   1
  descending  2

view_flags -- the second group of values can be added to one of the first group to combine effects,
with several limitations:
  Unthreaded       0
  Threaded         1
  Grouped         64  [mail only (?)]

  ShowIgnored      8  [news only]
  ShowUnreadOnly  16
  ShowExpanded    32  [doesn't seem to work]
ShowUnreadOnly will check the View|Threads|Unread menu; this will cause only
unread items to be seen, but doesn't force a threaded view.

Edit: of course, afterwards I find the add-on to do just this :)
Edit 2: Again, no convincing case… not sure if this works …
Edit 3: Nope, it doesn’t work. :(
Edit 4: see next post, kind of got it working.