apostrophe is replaced by other characters in replies

C

cyberpunk

If a user receives an email, then replies to it any apostrophes (') in
the reply get changed to an a with a carat over the top of it which is
a latin lower case A, then a Euro symbol, then the small TM for
trademark. Only certain users are seeing this.

I'd think it is due to a formatting or font problem, but all users are
using standard machines.

Any ideas?
 
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