I'm not sure what the email suspended cause: 550 #DKIM Signing Verification failed means. We sent out an email to a lead that resulted in a bounce, however, the email address is a valid address. Does anybody know what is happening in this particular scenario?
Derrick,
It looks like the domain used in the email's From address doesn't have DKIM set up. DKIM is an authentication method you want to set up so that the recipient's email server can verify that Marketo has permission to send email on behalf of your company. It prevents people from pretending to be at your company to steal information. Since it's not set up, it look's that recipient is outright rejecting the message because it appears suspicious.
Go to Admin > Email, click the SPF/DKIM tab, and add your domain:
Follow the instructions here for how to work with your IT team to get it set up:
Set up SPF and DKIM for your Email Deliverability - Marketo Docs - Product Docs
Grant
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