DKIM

[mark-harding]

Should DKIM pass ?

[mobizt]

It's up on MTA which is not client application related.

[mark-harding]

Thank you for your reply, Suwatchai.

I ask because apparently a dkim failure point is a non-matching from address:
A DKIM fail can occur if the DKIM signature header domain doesn’t match the domain found in the From header, which might be a typical case of domain spoofing or impersonation attack.
https://powerdmarc.com/why-does-dkim-fail/

From other clients, dkim passes:
Authentication-Results: mx.google.com;
dkim=pass [email protected] header.s=default header.b=jMjJQvvM;
and the from field is:
From: mark [email protected]

from my ESP_Mail_Client, dkim fails:
Authentication-Results: mx.google.com;
dkim=fail [email protected] header.s=default header.b=OUvlp3pA;
and the from field is:
From: "[email protected]" [email protected]

I am wondering if this might be the problem?

Thanks in advance

Mark

[mobizt]

If the SMTP server is already creating DKIM record and add to the DNS and the message was still rejected, you should consider what the host or IP you provide to this config.

ESP-Mail-Client/examples/SMTP/Send_Text/Send_Text.ino

Lines 162 to 170 in 1f4155c

	/** Assign your host name or you public IPv4 or IPv6 only
	* as this is the part of EHLO/HELO command to identify the client system
	* to prevent connection rejection.
	* If host name or public IP is not available, ignore this or
	* use generic host "mydomain.net".
	*
	* Assign any text to this option may cause the connection rejection.
	*/
	config.login.user_domain = F("mydomain.net");

You can assign your mail server domain or actually the loopback IP (127.0.0.1) should work.