Recipients can't read email attachments

Question

Scenario: Office full of Macs. All supposedly configured exactly the same (same OS, same version of Word, etc.) When one staff member creates then sends documents (so far Word and pdf docs), others can't read the attachments. The attachments, when opened in Word, look like gibberish.
The employee in question is using Mac Mail as the mail client. The others are using Thunderbird.
But here's the thing. When we take a file from the affected computer, put it on someone else's computer, then email it, the file comes over ok.
Also, we were able to test sending the same file from another Mac using Mac Mail and the file was okay.
I checked the mail preferences to see if he had the "Send Windows Friendly Attachments" option clicked. He did not.
Any ideas on where I should look to fix this problem?
Thanks.

Answer 1

Scenario: Office full of Macs. All supposedly
configured exactly the same (same OS, same version of
Word, etc.) When one staff member creates then sends
documents (so far Word and pdf docs), others can't
read the attachments. The attachments, when opened in
Word, look like gibberish.
The employee in question is using Mac Mail as the
mail client. The others are using Thunderbird.
So, the problem is in the Mac Mail set-up.
Have the user try changing some of the parameters.
Though Ernie has show himself to be smarter than I, I think that it has nothing to do with Exchange or anything besides how the Mac user using Mail.app has it configured, and -- so -- how the email is constructed and sent from that machine.
You said, "I checked the mail preferences to see if he had the "Send Windows Friendly Attachments" option clicked. He did not."
Okay. So set the option, restart Mail, and try it.
I have it set. I send Office docs, PDFs, everything, to people using every email client you can think of. I cannot think of one time I had a problem like this.
Fred