.. _response-codes:

==============
Response codes
==============

All
===

+------+------------------------------------------------------------+
| Code | message                                                    |
+======+============================================================+
| 220  | OK, ready                                                  |
+------+------------------------------------------------------------+
| 221  | Thank you for speaking to me                               |
+------+------------------------------------------------------------+
| 250  | OK, done                                                   |
+------+------------------------------------------------------------+
| 251  | OK, user not local, will forward                           |
+------+------------------------------------------------------------+
| 252  | OK, cannot VRFY user but will attempt delivery             |
+------+------------------------------------------------------------+
| 253  | OK, messages pending                                       |
+------+------------------------------------------------------------+
| 354  | Start mail input; end with <CRLF>.<CRLF>                   |
+------+------------------------------------------------------------+
| 355  | Octet-offset is the transaction offset                     |
+------+------------------------------------------------------------+
| 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    |
+------+------------------------------------------------------------+
| 454  | TLS not available due to temporary reason                  |
+------+------------------------------------------------------------+
| 458  | Unable to queue message                                    |
+------+------------------------------------------------------------+
| 459  | Not allowed: unknown reason                                |
+------+------------------------------------------------------------+
| 500  | Command not recognized                                     |
+------+------------------------------------------------------------+
| 501  | Syntax error, no parameters allowed                        |
+------+------------------------------------------------------------+
| 502  | Command not implemented                                    |
+------+------------------------------------------------------------+
| 503  | Bad sequence of commands                                   |
+------+------------------------------------------------------------+
| 504  | Command parameter not implemented                          |
+------+------------------------------------------------------------+
| 521  | Machine does not accept mail                               |
+------+------------------------------------------------------------+
| 530  | Must issue a STARTTLS command first                        |
+------+------------------------------------------------------------+
| 534  | Authentication mechanism is too weak                       |
+------+------------------------------------------------------------+
| 538  | Encryption required for requested authentication mechanism |
+------+------------------------------------------------------------+
| 550  | Requested action not taken: mailbox unavailable            |
+------+------------------------------------------------------------+
| 551  | User not local                                             |
+------+------------------------------------------------------------+
| 552  | Requested mail action aborted: exceeded storage allocation |
+------+------------------------------------------------------------+
| 553  | Requested action not taken: mailbox name not allowed       |
+------+------------------------------------------------------------+
| 554  | Transaction failed                                         |
+------+------------------------------------------------------------+
| 571  | Blocked                                                    |
+------+------------------------------------------------------------+

Accept
======

This mode will respond with the following codes:

+-------------------------+
| Codes                   |
+=======+=====+=====+=====+
| 250   | 251 | 252 | 253 |
+-------+-----+-----+-----+

Bounce
======

This mode will respond with the following codes:

+-------------------------------------------------+
| Codes                                           |
+=======+=====+=====+=====+=====+=====+=====+=====+
| 421   | 431 | 450 | 451 | 452 | 454 | 458 | 459 |
+-------+-----+-----+-----+-----+-----+-----+-----+
| 521   | 534 | 550 | 551 | 552 | 553 | 554 | 571 |
+-------+-----+-----+-----+-----+-----+-----+-----+

Offline
=======

This mode will respond with the following codes:

+-------+
| Codes |
+=======+
| 521   |
+-------+

Unavailable
===========

This mode will respond with the following codes:

+-------+
| Codes |
+=======+
| 421   |
+-------+