LTE Module Series
EC2x&EG9x&EM05 SMTP AT Commands Manual
EC2x&EG9x&EM05_SMTP_AT_Commands_Manual 28 / 31
6
Summary of SMTP Protocol Error
Codes
The protocol error code <protocol_error> indicates an error replied from SMTP server. Please refer to
RFC2821
(Simple Mail Transfer Protocol). The details about <protocol_error> are described in the
following table.
Table 2: Summary of SMTP Protocol Error Codes
<protocol_error> Meaning
421
Service not available, closing transmission channel
450
Requested mail action not taken: mailbox unavailable
451
Requested action aborted: local error in processing
452
Requested action not taken: insufficient system storage
500
Syntax error, command unrecognized
501
Syntax error in parameters or arguments
502
Command not implemented
503
Bad sequence of commands
504
Command parameter not implemented
521
<domain> does not accept mail (see
RFC1846
)
530
Access denied
535
Authentication failed
550
Requested action not taken: mailbox unavailable
551
User not local; please try <forward-path>
552
Requested mail action aborted: exceeded storage allocation
