how to get digital certificate informaiton of the email in mail adapter

Hi, expert:

I have a requirement to verify the validation of coming email with digital certification. The mail is with digital certification. If the coming email is valid, I 'll get the attachemt of the mail for further processing. I have a sender mail adapter and receiver file adapter configued.

I have already my own developed adapter module, which is configued in mail adapter. My question is how to retrieve the detailed certificate information in the adapter module developed by myself. Is it feasible?

Thanks a lot.