All emails that pass through SMTPeter are now automatically DKIM signed by SMTPeter, using the private key of SMTPeter. This is an extra signature that is added to your emails alongside your own signatures.
The DKIM specification allows emails with multiple DKIM signatures. We use this feature to add the SMTPeter signature alongside any of your own DKIM signatures. It is therefore very well possible that your receivers will get an email that is both signed with your own private key as well as with the private key of SMTPeter.
Why do we do this?
By adding the extra signature, we add trust to your email. A receiver can not only check whether the email was correctly signed with your private key, but it can also see that the mail was correctly processed by the SMTPeter servers.