# RFC 5321 ยง4.3: out-of-sequence commands must return 503.
S: 220
C: EHLO test
S: 250-
S: 250-PIPELINING
S: 250-SIZE
S: 250-8BITMIME
S: 250-SMTPUTF8
S: 250-ENHANCEDSTATUSCODES
S: 250-AUTH PLAIN LOGIN
S: 250 HELP
# RCPT before MAIL FROM
C: RCPT TO:<a@b>
S: 503
# DATA before MAIL FROM
C: DATA
S: 503
C: MAIL FROM:<x@y>
S: 250
# DATA before RCPT
C: DATA
S: 503
C: QUIT
S: 221