4.1.3

Delayed Message: email address malformed

The email message has not yet been delivered because the recipient's email address is not a valid email address.

Fixes

Check the recipient's email address for spaces or unusual characters. If an error is found, correct it in contacts list or address book for next time.

If necessary, contact the recipient another way (e.g., phone or text message) to confirm their email address.

4.1.3: Official Definition

4.X.X

[RFC3463] (Standards Track) from the The Internet Engineering Task Force (IETF) definition for codes that start with 4.X.X:

A persistent transient failure is one in which the message as sent is valid, but persistence of some temporary condition has caused abandonment or delay of attempts to send the message. If this code accompanies a delivery failure report, sending in the future may be successful.

X.1.3

[RFC3463] (Standards Track) from the The Internet Engineering Task Force (IETF) definition for codes that end with X.1.3:

The destination address was syntactically invalid. This can apply to any field in the address. This code is only useful for permanent failures.

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