Why It Matters
Forwarding is essential for managing multiple email addresses without checking each one separately. Businesses use it to route support@, sales@, and info@ to the right team members. Individuals use it to consolidate personal and work accounts. But forwarding has a gotcha that matters for email marketers: it can break SPF authentication, which causes deliverability problems for the original sender.
How It Works
When a server forwards an email, it re-sends the message from its own IP address. The problem: SPF checks the sending IP against the original sender's authorized list. Since the forwarding server's IP isn't on that list, SPF fails. DKIM usually survives forwarding (as long as the message body isn't modified), and DMARC alignment depends on which authentication method passes. SRS (Sender Rewriting Scheme) is a workaround that rewrites the envelope sender to fix SPF, but not every forwarding server implements it.
Quick Tips
- If you forward email, make sure DKIM is set up on your sending domain — it's the authentication method most likely to survive forwarding
- Use IMAP fetch instead of forwarding when possible; it avoids the authentication issues entirely
- Test your forwarding setup by sending a message and checking the headers at the destination to confirm authentication results