>> is this sufficient?
>>
>> open location "mailto:[log in to unmask]
>> 20Man&[log in to unmask]&X-Honk=if%20you%20love%
>> 20hidden%20Headers"
>>
>> -Mark
>> Hasn't hid things in headers in a while.
> I second the call to use mailto, but I would note that attachments in
> a mailto link are almost always ignored as a security risk.

If you really want to do attachments, I suppose you could use a link open location "mailto...." to get the message created in the default app. Then, you could determine which app is now frontmost and have appropriate code for each possible (supported by you) email client to add your attachment. 

Not trivial, but doable. 

Daniel A. Shockley
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http://www.danshockley.com