Earlier on I decided to add my new live mail account to Thunderbird. All went well until I clicked Get Mail; shortly after, an error message popped up helpfully informing me that:

[…] live.co.uk is a unsupported domain.

A quick google search on that text didn’t turn up anything directly useful, but did remind me that the Hotmail add-on has options for selecting between the old and new version’s connection method.  Unfortunately, that was correctly set for Hotmail Live (New website), but when I looked in Webmail‘s options I noticed a Domain tab that listed, appropriately enough, the supported domains.  Hotmail and MSN had .co.uk entries but there was nothing for live.co.uk and no obvious way to add a custom entry.

Haha!  A chance for some extension hacking, I thought, and set about locating the add-on in the Thunderbird profiles directory.  In Windows XP, it’s:

C:\Documents and Settings\<YOUR_USERNAME>\Application Data\Thunderbird\Profiles\<8_RANDOM_CHARACTERS>.default\extensions\{a6a33690-2c6a-11d9-9669-0800200c9a66}

In that directory is a file called domains.txt, which lists the supported domains for the Hotmail add-on.  Adding in the line:

<domain>live.co.uk</domain>

and then restarting Thunderbird fixed the problem, and a few seconds later my e-mails flooded in.