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emailsslssl-certificatesigningmta

How and where does SSL signing apply to emails?

I am trying to find out how SSL signing of emails work and if it gets signed server side or MTA side? I know this is a bit vague maybe but any resources to read or documentation would help a lot :D

Like for example I use a ezComponents mail object to send a mail object to the MTA server. DO I have to sign the mail object inside of PHP by using something

OR

Does the signing happen on the sending server (MTA)?

Just to add some clarity, I would like to use this functionality to send secure emails to customers for their monthly statements and reports. But implementation is irrelevant at this stage, I am interested in docs and resources and wisdom from people that knows :D

EDIT: Okay so I am using S/MIME. does anybody have an idea how to do this? I can't find any good PHP examples.

Solution

  • SSL is a transport protocol, and there's no such thing as "SSL signing of e-mails". This is why you can't find anything.

    Signing of e-mail is done using S/MIME standard. Signing is performed by the sender application using sender's X.509 certificate with a corresponding private key. IF the SMTP server has all certificates with keys, it can sign e-mail on behalf of the sender. This is sometimes used in corporate environments.