[Macpartners] MIME Types with Eudora and OS X

[Albert Willis]

On Nov 8, 2005, at 9:09 AM, Christopher Naylor wrote:

> Does anyone know how to change the MIME mapping for Eudora 6.2.3 on  
> OS X?  The manual describes using ResEdit to edit the resource  
> fork, but that sounds strangely OS 9-ish; the included illustration  
> in the manual is of a OS 9 window.  My postings in the Eudora  
> forums gets looks but no replies.
>
> Anyway, the reason I ask is this.  I have a user who sends lots of  
> PDF files back and forth with collaborators by email.  Recently,  
> his collaborators began to complain that some of his PDFs, coming  
> through as email attachments, could not be opened.  So the user  
> came to me for help.
>
> First off, Eudora was adding the ".ai" suffix to the file name.  So  
> a file "Paper.PDF" was being decoded at the recipicient's end as  
> "Paper.PDF.ai".  Remove the ".ai", and the file opened just fine.   
> The files were coming through OK.  Oddly enough, this file name  
> change happened to SOME, not ALL, his PDF files sent.  Eudora was  
> sending them all as AppleDouble (MIME) encoded documents, without  
> the macintosh information.
>
> His OS recognized PDFs as being Adobe Acrobat Reader documents.  He  
> can double-click them, and they open up fine in Acrobat Reader.   
> The OS displays the proper icon with the files.
>
> I examined the file type and creator for the PDFs and found  
> something interesting.  PDFs with the proper file type and creator  
> were the ones that Eudora added the ".ai" to.  PDFs with improper  
> or missing file type and creator data went just fine.  Probably  
> Eudora just encoded those missing-data files and sent as-is.  The  
> solution seemed to be to find the MIME mappings for Eudora, and  
> make a change.

What I suspect is happing is Eudora is using the creator and type of  
the file to determine how to treat it. PDFs created by Acrobat have a  
creator of 'CARO' and type of 'PDF '. Prior to Mac OS X, Macs used  
the creator and type of a file to determine what application can open  
it. To be compatible with Windows and Unix, Mac OS X uses file name  
extensions (like .doc for a Microsoft Word file) to bind the file to  
the applications that can open it. Eudora, since it was written long  
before Mac OS X existed, is likely using the creator and type of the  
PDF to determine what suffix should be added to the file when it's  
being sent--it appears to adding the .ai file extension (which is for  
an Adobe Illustrator file) when the complete type and creator isn't  
available.

A user that receives a file that ends in .ai will have a hard time  
opening it, since the computer will think it's something other than a  
PDF.
>
> Easier said than done.  I deleted and recreated his settings.  I  
> deleted .plist files from his Library.  I did everything but  
> reinstall the application.  Nothing worked.
>
> So I turn to you for help.  Any ideas?

The short term solution is to make sure your PDF files have the  
'proper' creator and type, so that Eudora will handle it correctly.  
The easiest way to to use XRay (http://www.brockerhoff.net/xray/),  
which can change the creator and type for multiple files at once. You  
can also write an AppleScript to do the same thing.

The longer term solution is to use Mail (http://www.apple.com/macosx/ 
features/mail/), which sends PDFs correctly and uses Apple's new  
metadata system for Mac OS X 10.3 and above, Uniform Type Identifiers  
(UTIs), which solves the problem of file name extensions, type and  
creator, etc. There's a good description of UTIs at Ars Technica  
(http://arstechnica.com/reviews/os/macosx-10.4.ars/11).

   -- Al


______________________________
Albert Willis
Macintosh Platform Coordinator - Software Release Team
Information Services and Technology
Massachusetts Institute of Technology
awillis at mit.edu


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.mit.edu/pipermail/macpartners/attachments/20051109/3a55820d/attachment.htm