Can't send/receive mail with SendGrid and forwarding on: 550 The from address does not match a verified Sender Identity.

• This message is in /var/log/maillog

  postfix/smtp[653]: to=john.doe@example.com, relay=smtp.sendgrid.net[13.114.210.107]:587, delay=1.6, delays=0.01/0.01/1.3/0.35, dsn=5.0.0, status=bounced (host smtp.sendgrid.net[13.114.210.107] said: 550 The from address does not match a verified Sender Identity. Mail cannot be sent until this error is resolved. Visit https://sendgrid.com/docs/for-developers/sending-email/sender-identity/ to see the Sender Identity requirements (in reply to end of DATA command))

• The affected email account has forwarding enabled in Domains > example.com > Mail > Mail Accounts > john.doe@example.com > Forwarding

Cause

Plesk sets the original sender in the forwarded email's From header, while SendGrid expects the forwarder domain instead, and rejects it if it doesn't match.

Resolution

SendGrid needs to allow the original sender, or forwarding has to be set up elsewhere. These options are available:

• Set up forwarding in webmail or a mail client by following its documentation. If it works differently, it may use a From header that SendGrid will accept.
• Contact SendGrid support for options to allow email when the From header's address is different from the verified domain due to forwarding.