"mmblanco5" wrote in message
...

In the Options dialog I selected S/MIME settings for the user. I have
selected the personal certificate for sign and encryption purposes signing
with SHA1 method and encrypting with 3DES method.
I hav also checked the settings from Internet Explorer you suggested and
YES, I'm able to export the certificate private key.

Then it looks to me like the recipient replying with his or her own
encrypted message may have an invalid certificate for you. What I would
suggest is that you ask your recipient to remove your Contact record from
the Contacts folder, your address from the autocompletion cache, and your
existing certificate from their "Other People" certificate store. Then you
should send a new signed message and they should right-click your address on
that message and choose Add to Contacts. This should reload your public key
into their certificate store. Have them try to send you another encrypted
message after that.
--
Brian Tillman [MVP-Outlook]