NDR error code 550 5.1.20 "Multiple From addresses are not allowed without Sender address"
This NDR is generated if an email message has multiple email addresses in the From field, but no email address in the Sender field. For more information, see RFC 5322 - Originator fields.
How do I fix this?
In general, don't send email messages that have multiple addresses in the From field because many email clients don't support this configuration. Email messages that have multiple email addresses in the From field are rare.
If you must send a message that has multiple email addresses in the From field, make sure that you have a single email address in the Sender field. If you're unsure about how to configure your message correctly, ask your email admin.
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