This article has recommendations for email administrators and Gmail users who forward messages from other accounts or services to Gmail. Forwarding email messages can affect email authentication. Follow the recommendations in this article to increase the likelihood that forwarded messages pass authentication and are delivered as expected.
Email administrators: If you’re an email administrator who forwards email to Gmail from other servers or services, take steps to ensure Gmail correctly marks forwarded messages as legitimate or spam. Follow our recommendations in the section Email forwarding for administrators.
Email senders: We always recommend that senders set up SPF and DKIM authentication. For forwarded messages, DKIM authentication is especially important to help ensure your email is delivered as expected. Learn more
Gmail users: If you forward messages from a non-Gmail account to your Gmail account, follow our recommendations in the section Email forwarding for Gmail users.
Email forwarding for administrators & senders
If you manage email for your organization and you forward email from other servers or services to Gmail, follow the recommendations in this section to ensure email is delivered as expected.
Help prevent forwarded messages from being marked as spam
These practices help ensure messages forwarded to Gmail pass SPF authentication, reducing the likelihood that Gmail marks messages as spam:
- Change the envelope sender to reference your forwarding domain.
- Make sure your domain's SPF record includes the IP addresses or domains of all servers or services that forward email for your domain.
- Use third-party products or services to identify spam messages, and prevent them from being forwarded. If forwarded messages from your domain are marked as spam by recipients, future messages from your domain are more likely to be marked as spam.
- Consider using a unique domain or IP address to forward messages. This is one of our recommendations for preventing email to Gmail users from being blocked or sent to spam.
- Set up SPF and DKIM email authentication: We recommend email administrators always set up SPF and DKIM email authentication for their domain. Email forwarding can affect message authentication, and forwarded messages often fail SPF authentication. This is why we recommend you always set up DKIM authentication, along with SPF, to help ensure your messages are authenticated and delivered as expected.
- Avoid breaking DKIM authentication: Messages that don't pass DKIM are more likely to be sent to spam. Changes to message contents can cause messages to fail DKIM authentication. Avoid changing the body and message headers protected by DKIM. For messages sent from frequently spoofed domains, Gmail enforces strict authentication requirements. The following actions can cause forwarded messages to fail DKIM:
- Modifying the MIME boundaries
- Modifying the message Subject
- Third-party software modifying the body of the message (including re-encoding the message)
- Expanding message recipients with LDAP
- Modifying the Subject and other headers protected by the DKIM signing domain (including To, Cc, Date, and Message-ID)
- Add ARC headers: To reduce the likelihood that forwarded messages are rejected or marked as spam, we recommend you add ARC headers to forwarded messages. ARC verifies previous authentication checks for forwarded messages, and helps ensure forwarded messages are delivered to the final recipients. Learn more about ARC.
- Add forwarding headers: To let email servers know that a message is forwarded, add an X-Forwarded-For: or X-Forwarded-To: message header. Receiving servers manage forwarded messages differently than direct, incoming messages.
If you forward messages from other email accounts to your personal Gmail account, follow the recommendations in this section to help ensure messages are delivered correctly:
- Set up IMAP or POP in your Gmail account: IMAP lets you read messages on multiple devices, and messages are synced in real time. POP lets you get messages on a single device, and messages aren't synced in real time. Instead, they're downloaded and you decide how often you want to download new emails. For detailed steps to set up IMAP or POP with your Gmail account, visit Check emails from other accounts.
- Mark or unmark spam messages: When Gmail incorrectly marks a message as spam or phishing, fix the mistake by following the steps in mark or unmark messages as spam. This helps Gmail correctly identify spam and legitimate messages in the future.
- Update your Gmail settings: If you forward messages from another email account to your Gmail account, Gmail might incorrectly mark some messages as spam or phishing. To help prevent this, add your non-Gmail address to Gmail’s Send mail as setting. For detailed steps, visit Send emails from a different address or alias.