Modifying the contents of a message

Kent James kent at
Fri Jan 27 16:10:37 UTC 2012

On 1/26/2012 4:55 PM, Unicorn.Consulting wrote:
> On 27/01/2012 1:49 AM, Jonathan Protzenko wrote:
>> Hi everyone,
>> Ever since I started reading the and 
>> newsgroups, a recurring question about 
>> Thunderbird has been "how can I modify the contents of a message" 
>> from an addon? I recently (less than 7 days ago) replied to this 
>> question twice, and my answer was basically:
>> - inject a message in a local folder,
>> - copy it to the destination folder,
>> - remove the old message.
>> I'm not sure there's a better way, but I guess not. My question is: 
>> could we make that easier by implementing, say, in C++, 
>> nsIMsgFolder::InjectMessageFromStream, making it of course 
>> scriptable? The arguments are:
>> - this is something an addon will want to do, and it seems legitimate 
>> that they should want to do so,
>> - it's better to provide a function for that than to have someone do 
>> it real, real wrong.
>> I'm not very familiar with that area, so I'd be interested in hearing 
>> what others have to say on the matter :).
> When I send my signed message to someone, or SMIME message, I would 
> like to think that I don't have to produce my copy to prove what I 
> sent to the recipient as a matter of course.  If your going to use 
> this type thing, and I can understand where editing the subject may be 
> valid, I would like to see the digital signature removed by 
> Thunderbird if the content is changed.
> Microsoft Outlook, which is the application sited most when people are 
> asking for this, will not save an existing signed mail without you 
> also having a digital signature,  I assume it replaces the signature 
> as a part of the edit.
> Certainly there is always the opportunity for a message to be modified 
> in a text editor, but please lets try and make fraudulent 
> modifications as hard as possible. As I understand it a digitally 
> signed message is a legal document in the EU.  Should we be making the 
> modification (without obvious forensic fingerprinting of the process) 
> a simple process for add-on authors to execute.

When reviewing addons that modify messages, I have not known what to 
require with respect to original message integrity. I would welcome 
suggestions along this line. But I am not the only reviewer of 
Thunderbird addons, and it is not easy to communicate reliably 
requirements such as maintaining message integrity to all editors.

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