Email servers and the MAIL FROM syntax

If you’re into chatting with SMTP servers via telnet ( only for debugging purposes, I swear :p ), be aware that some new email servers strictly interpret RFC 2821 and appears to reject MAIL FROM and RCPT TO addresses of the form [email protected]. Instead, it will return a 555 5.5.2 Syntax error. The proper solution is to enclose the address brackets, as in <[email protected]>.

A redacted transcript:

250 Hello
MAIL FROM: [email protected]
555 5.5.2 Syntax error.
MAIL FROM: <[email protected]>
250 2.1.0 OK
RCPT TO: [email protected]
555 5.5.2 Syntax error.
RCPT TO: <[email protected]>
250 2.1.5 OK


I’m sure this is intended so that clients that send “Joe Schmoe <[email protected]>” are correctly interpreted. I’m not sure if the RFC asks for this strict enforcement (on my admittedly cursory reading), though and yet a fair number of servers are rejecting the alternate address-only syntax. Wacky.

8 Replies to “Email servers and the MAIL FROM syntax”

  1. The helped to a point but I still get Message received from STMP server : 555 5.5.2 Syntax error. v3si5396111qth.170 – gsmtp
    Index:2 frmCommunication:sckSMTPconnection_DataArrival

Leave a Reply

Your email address will not be published. Required fields are marked *