Google has recently notified us about an upcoming change to our institution’s Gmail services. Starting April 24, 2023, Gmail will begin rejecting messages that contain more than one RFC-mandated single-instance header in order to better protect against spam and abuse. These messages will be rejected with the error message: “This message is not RFC 5322 compliant.”
What do you need to do?
If you or your third party vendors generate emails that include multiple single-instance headers, you will need to modify how you generate the emails to include at most one instance of each. RFC-mandated single-instance headers are as follows:
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To
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Cc
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Subject
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Date
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From
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Sender
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Reply-To
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Bcc
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Message-ID
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In-Reply-To
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References
Note: The Internet Official Protocol Standards: Internet Message Formats [Request For Comments (RFC) 5322] states that a message must have at most one instance of each of the above headers. Please see RFC Editor’s Internet Message Format RFC 5322 document for additional information on the headers that are standards-compliant.
For additional information, please consult Google’s documentation “Prevent mail to Gmail users from being blocked or sent to spam”
If you have questions or need assistance, please contact the ITS Help Desk.