Hi, Microsoft Exchange Online rejects messages with multiple From addresses if there's no Sender address specified per https://learn.microsoft.com/en-us/exchange/troubleshoot/email-delivery/ndr/fix-error-code-550-5-1-20-multiple-from-addresses This is in relation to https://www.rfc-editor.org/rfc/rfc5322#section-3.6.2
Is there a way for postfix to implement the same policy (for this MTA instance, postfix is in front of Exchange and we want postfix to reject the message before relaying to Exchange) AI suggested putting: ``` /^From:.*@.*,.*@.*$/ /^(?!.*^Sender:.*$)/ REJECT Multiple From addresses without a Sender header ``` in `header_checks`, but I don't think that will work since headers are checked one line at a time... What's the best way to do this? Thanks, -Matt _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
