Anyway

My major cli­ent uses mostly Microsoft products: Out­look + Exchange and Office. It turns out that the com­pat­ib­il­ity with Open­Of­fice is lim­ited when it comes to large doc­u­ments and defined styles, so I upgraded my old Office 2003 to Office 2010 on my Win­dows 7 PC desktop. And then ran into anoth­er prob­lem: file cor­rup­tion in email attachments. 

I use Thun­der­bird 3 to fetch mail via IMAP from the Exchange serv­er, but every time someone sent me a Word doc­u­ment, I’d get this error mes­sage about not being able to open it in Word 2010 because it was cor­rup­ted. If I used the Out­look Web Access cli­ent it worked fine, so it was­n’t a cor­rup­tion at the serv­er. And Word 2003 used to open the same types of doc­u­ments sent to me by the same per­son, so at first I wondered if it was some­thing to do with Word’s upgrade.

Hunt­ing around Moz­il­la’s getsatisfaction.com web site gave me a point­er to Spe­cial Thun­der­bird IMAP Set­tings at the Michigan State Uni­versity’s Phys­ics-Astro­nomy Com­put­ing Sup­port Site (they have inter­est­ing art­icles on lots of related issues). Basic­ally, the issue is due to Thun­der­bird chunking the file as it pulls it down from the serv­er, which intro­duces some cor­rup­tion. The same appar­ently also applies to using the Gmail IMAP serv­er, although I haven’t noticed any issues with that. 

To fix it, go into Tools…Options. Select the Advanced tab, click on “Con­fig Edit­or”. Search for chunks. Click on the res­ult­ing set­tings to make sure they’re all set to “user set” “false” (they will be in bold once this is done). Close the win­dow and press OK to save. I then restar­ted Thun­der­bird to be on the safe side (not all con­fig set­tings take effect without a restart and I did­n’t feel like test­ing it). Then (and the web page I linked to did­n’t include this step), right-click on the account name in the list of accounts/folders on the left (in the stand­ard win­dow con­fig­ur­a­tion), and choose “Prop­er­ties”. You should see a “Repair Folder” but­ton. Click on this to make Thun­der­bird fetch everything again, with the new settings.

Prob­lem solved! I still don’t know why Word 2010 had prob­lems with doc­u­ments that Word 2003 could read, but I don’t care enough to try to find out.