In the Mail Processing menu, the manner of the processing of emails is configured. Here, the default ruleset can be adapted to the individual requirements, if applicable.

 

To ensure that the email routing by means of "Exchange Online" "rules" can be guaranteed, the following X-headers are already set by default, i.e. without any additional change to the configuration being necessary:

 

X-SM-incoming=yes

X-SM-outgoing=yes

X-SM-internal=yes

X-SM-encrypted=yes

X-SM-decrypted=yes

 

Whether a special configuration is required for connecting the SEPPmail Secure E-Mail Gateway to Microsoft 365/Exchange Online depends on security settings in Microsoft 365.

 

If, for example, "DKIM" is used, the DKIM signature, which is set during the first run through "Exchange Online" (see also Outgoing Email Flow), must be removed, as the email may be handled cryptographically and thus modified by the SEPPmail Secure E-Mail Gateway. "Exchange Online" will append the DKIM signature again on the second run.

 

To delete the first DKIM signature on the SEPPmail Secure E-Mail Gateway, the following code must be entered under Custom commands for outgoing e-mails BEFORE encryption.

 

Code

 

For incoming email flows, it should be noted that signatures must be truncated (at least Remove signature if S/MIME signature check succeeds) if verification options are active in Microsoft 365 that change the email content the second time it is received.

This change would inevitably destroy any signature still attached to the email. This in turn would lead to different verification results on SEPPmail and the Outlook client, at least for signatures verified as valid by SEPPmail.

 

In order to generally prevent different check results between SEPPmail and the email client, we recommend generally truncating the signatures, see hint at Remove signature if S/MIME signature check succeeds.