Issue
Support for DKIM was added to the service-now.com domain in late 2017. With DKIM enabled, the ServiceNow (service-now.com) email servers sign outgoing messages using a private key.
Receiving mail servers can then use a public key, published on the service-now.com DNS record, to verify the signatures on any emails sent out from the ServiceNow (service-now.com) email servers.
By default, DKIM signing will only work for emails where the From: address is something@service-now.com. For customer domains while using ServiceNow email servers, please see KB1002273.
Release
NA
Resolution
DKIM public Keys are stored the Service-now.com DNS:
The current DKIM Public key records are found using the "DKIM Selector" value with in the DNS.
The "DKIM Selector" values are referenced in the header information sent by ServiceNow Email Servers.
How to obtain the "DKIM Selector" value from an email header:
Example email header:
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=service-now.com; s=20210504; t=1641841077;
The "DKIM Selector" is referenced with in the "s=" value, (s=20210504) so in this example it is: 20210504
There are many websites that let you check DNS-related records such as SPF or DKIM for a domain.
So using the "DKIM Selector value" (example: 20210504) and the sender domain "service-now.com"
You can run a DNS check on this website: https://www.mail-tester.com/spf-dkim-check
Retrieving the "DKIM public key" from the service-now.com DNS using the command line:
This "DKIM Selector" value can be used running the following command from a UNIX/MacOS computer to retrieve the public Key:
dig 20210504._domainkey.service-now.com TXT +short
"v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwZZerAE5ghMvKjbmPHLB282v5ugk9ll9vyJJtSc72Ttx2J6wAmL1pE50UQeapDgruYUou6BPQXMhVi3LfOU/uRuhY2D9x0PXHio2cjzqO/Kmd+jDm7mSztTfMrsdd9FthAMfcSemt65ElAfDbjH/" "erK1TR5jqN5Ng0WUsGf6PiO7sIYL09asf5n4UK+AjVheYl5ZJefSDVae2XYfjmfHGGYbJrR4MaRrlOF2FQgOpWhU8buy0TwAKPalOAgjXLWWYxDa7w+iU7YrTNjucTwGHEpGvPt8WqbtlivH0JNHWYM3vJ5PgxVW9JRx6SalYfb3B0OH4lBi2dgOv6okIWNFJwIDAQAB"
Related Links
Some companies request DKIM keys so that they can send emails with From: addresses such as something@customer.com while using the ServiceNow SMTP server. Please see KB1002273 on how to request this.
