Email Client Template fails with custom From address (450 4.1.8 Sender address rejected)

[vguadagni]

Hello everyone,

Hope you can help with an issue I am currently facing.

We were asked to use a different “From” address for specific types of emails, specifically for some Email Client Templates.
The instance in question normally uses the default ServiceNow sender address (e.g. example@service-now.com).

After some initial difficulties, the emails were being sent from the instance but, in most cases, they were not received by the recipients.

Following this guide (which complements official documentation that is missing some details):
https://www.servicenow.com/community/developer-blog/make-sure-your-email-is-received-with-dkim-and-s...

we addressed the spoofing issues.

Once the DKIM and SPF records were correctly published in DNS by our email team, a new problem appeared.

At this point, all other emails sent from the instance work without any issues. The problem occurs only when sending emails via an Email Client Template that uses this custom “From” address.

When this happens, the emails are not sent at all. In the sys_email table, they remain in the status “send-retry-delayed”, and when I open a specific record, the Error string shows:

450 4.1.8 <customerservice@esempio.com>: Sender address rejected: Domain not found

I am not particularly experienced with email infrastructure, so I would like to ask if anyone has encountered a similar issue before. I could not find anything relevant to this specific case in the community or in the official documentation.

Thank you in advance for your help.