POP3 connect to localhost

Question

Hi,

When trying to connect to a localhost (127.0.0.1) Pop3 server I get a ProtocolError saying: "Command not supported"

Do you not support connections to localhost, or is there a way to get around this?

The communication log looks like this: 2010-25-08 11:16:03.020 Opening log file.

2010-25-08 11:16:03.020 INFO Pop3(2) Info: Connecting to 127.0.0.1:110 using Pop3 1.0.3588.0.

2010-25-08 11:16:03.020 DEBUG Pop3(2) Info: Connection succeeded.

2010-25-08 11:16:03.020 INFO Pop3(2) Response: +OK POP3 Dualog Communicator Internet Agent ready

2010-25-08 11:16:03.020 INFO Pop3(2) Command: CAPA

2010-25-08 11:16:03.020 INFO Pop3(2) Response: +OK Capability list follows

2010-25-08 11:16:03.020 INFO Pop3(2) Command: APOP xxx@xxx.com 4bd2982ad4fc288506d1d5a62af4f609

2010-25-08 11:16:03.020 INFO Pop3(2) Response: -ERR command not supported

2010-25-08 11:16:03.020 ERROR Pop3(2) Info: Rebex.Net.Pop3Exception: command not supported ved Rebex.Net.Pop3.1810748823(Boolean , Boolean , String& ) ved Rebex.Net.Pop3.20949316419(String , Boolean , Boolean ) ved Rebex.Net.Pop3.1634555338(String , String , Pop3Authentication , GssApiProvider ) ved Rebex.Net.Pop3.Login(String userName, String password, Pop3Authentication method)

The POP3 server is from Dualog

Answer 1

Connections to localhost are fully supported. Which POP3 server are you running on localhost? Could you please edit your question and include communication log as described in http://www.rebex.net/kb/logging.aspx so we can see which command triggered the "Command not supported" response? Alternatively you can send the log to support@rebex.net for analysis.

EDIT:
It seems that the original issue was caused by the Rebex POP3, which incorrectly used APOP command. In current version, the APOP is used only for servers which include a timestamp in its banner greeting. Examples:

+OK POP3 server ready <1896.697170952@dbc.mtview.ca.us>

or:

+OK <dciaserv> POP3 Dualog Communicator Internet Agent ready

To explicitly disable APOP feature, set the Pop3.Settings.DisableApopAuthentication to true.

Comments

Hi Martin,
I have a similar error with Dualog POP3. here below the log received from TELNET

+OK <dciaserv> POP3 Dualog Communicator Internet Agent ready
user username@isn.dualog.net+OK user has mailbox
pass xxxxxxx
+OK maildrop locked for user
list
+OK messages list follows
1 3766
2 3766
3 3785
4 9490
5 20245
6 20249
7 20360
8 22137
.
retr 1
+OK message 1 follows
Received: from dualog.net(remoteHostName) by DUALOGSERVER.localhost with DCS (Du
alog DCS); Thu, 02 Mar 2017 15:23:20 +0000
Received: from MX2.dualog.no(<ukjent>) by TASK01. with SMTP (Dualog SMTP); Thu,
02 Mar 2017 15:04:06 +0000

Thank you in advance for any suggestions.
David

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Hello David. Unfortunately, I cannot see, what is wrong from the TELNET log. Can you please post here the log produced by our component: http://www.rebex.net/kb/logging.aspx
Thank you

---

Here it is the log direct from the field.
Thank you very much for your quick answer.

------------------------------------------------------------------------

2017-03-06 15:35:51.086 Opening log file.
2017-03-06 15:35:51.088 Using FileLogWriter version 2.0.5584.0.
2017-03-06 15:35:56.833 DEBUG Pop3(1)[3] Info: State changed from 'Disconnected' to 'Connecting'.
2017-03-06 15:35:56.846 INFO Pop3(1)[3] Info: Connecting to 192.168.60.10:110 using Pop3 2.0.5584.0.
2017-03-06 15:35:56.888 DEBUG Pop3(1)[3] Info: Connection succeeded.
2017-03-06 15:35:56.888 DEBUG Pop3(1)[3] Info: State changed from 'Connecting' to 'Reading'.
2017-03-06 15:35:56.897 VERBOSE Pop3(1)[3] Info: Received data:
 0000 |2B-4F-4B-20-3C-64-63-69 61-73-65-72-76-3E-20-50| +OK <dciaserv> P
 0010 |4F-50-33-20-44-75-61-6C 6F-67-20-43-6F-6D-6D-75| OP3 Dualog Commu
 0020 |6E-69-63-61-74-6F-72-20 49-6E-74-65-72-6E-65-74| nicator Internet
 0030 |20-41-67-65-6E-74-20-72 65-61-64-79-0D-0A      |  Agent ready..
2017-03-06 15:35:56.898 INFO Pop3(1)[3] Response: +OK <dciaserv> POP3 Dualog Communicator Internet Agent ready
2017-03-06 15:35:56.898 DEBUG Pop3(1)[3] Info: State changed from 'Reading' to 'Ready'.
2017-03-06 15:35:56.903 DEBUG Pop3(1)[3] Info: State changed from 'Ready' to 'Sending'.
2017-03-06 15:35:56.904 VERBOSE Pop3(1)[3] Info: Sent data:
 0000 |43-41-50-41-0D-0A                              | CAPA..
2017-03-06 15:35:56.905 INFO Pop3(1)[3] Command: CAPA
2017-03-06 15:35:56.905 DEBUG Pop3(1)[3] Info: State changed from 'Sending' to 'Reading'.
2017-03-06 15:35:56.905 VERBOSE Pop3(1)[3] Info: Received data:
 0000 |2B-4F-4B-20-43-61-70-61 62-69-6C-69-74-79-20-6C| +OK Capability l
 0010 |69-73-74-20-66-6F-6C-6C 6F-77-73-0D-0A-54-4F-50| ist follows..TOP
 0020 |0D-0A-55-53-45-52-0D-0A 55-49-44-4C-0D-0A-2E-0D| ..USER..UIDL....
 0030 |0A                                             | .
2017-03-06 15:35:56.905 INFO Pop3(1)[3] Response: +OK Capability list follows
2017-03-06 15:35:56.905 DEBUG Pop3(1)[3] Info: State changed from 'Reading' to 'Downloading'.
2017-03-06 15:35:56.906 DEBUG Pop3(1)[3] Response: TOP
2017-03-06 15:35:56.906 DEBUG Pop3(1)[3] Response: USER
2017-03-06 15:35:56.906 DEBUG Pop3(1)[3] Response: UIDL
2017-03-06 15:35:56.906 DEBUG Pop3(1)[3] Response: .
2017-03-06 15:35:56.906 DEBUG Pop3(1)[3] Info: State changed from 'Downloading' to 'Ready'.
2017-03-06 15:35:56.963 DEBUG Pop3(1)[3] Info: State changed from 'Ready' to 'Sending'.
2017-03-06 15:35:56.963 VERBOSE Pop3(1)[3] Info: Sent data:
 0000 |41-50-4F-50-20-61-72-6F 72-2E-75-62-63-2E-63-61| APOP aror.ubc.ca
 0010 |72-74-61-67-65-6E-61-40 69-73-6E-2E-64-75-61-6C| rtagena@isn.dual
 0020 |6F-67-2E-6E-65-74-20-37 62-36-33-36-66-65-63-31| og.net 7b636fec1
 0030 |65-32-34-65-65-33-61-31 64-35-61-30-34-66-62-33| e24ee3a1d5a04fb3
 0040 |30-37-30-31-30-62-63-0D 0A                     | 07010bc..
2017-03-06 15:35:56.963 INFO Pop3(1)[3] Command: APOP aror.ubc.cartagena@isn.dualog.net 7b636fec1e24ee3a1d5a04fb307010bc
2017-03-06 15:35:56.963 DEBUG Pop3(1)[3] Info: State changed from 'Sending' to 'Reading'.
2017-03-06 15:35:56.964 VERBOSE Pop3(1)[3] Info: Received data:
 0000 |2D-45-52-52-20-63-6F-6D 6D-61-6E-64-20-6E-6F-74| -ERR command not
 0010 |20-73-75-70-70-6F-72-74 65-64-20-0D-0A         |  supported ..
2017-03-06 15:35:56.964 INFO Pop3(1)[3] Response: -ERR command not supported
2017-03-06 15:35:56.964 DEBUG Pop3(1)[3] Info: State changed from 'Reading' to 'Ready'.
2017-03-06 15:35:56.968 ERROR Pop3(1)[3] Info: Rebex.Net.Pop3Exception: command not supported
   at Rebex.Net.Pop3.UZ(Boolean A, Boolean B, String& C)
   at Rebex.Net.Pop3.LU(String A, Boolean B, Boolean C)
   at Rebex.Net.Pop3.CV(String A, String B, Pop3Authentication C, GssApiProvider D)
   at Rebex.Net.Pop3.IP(String A, String B, Pop3Authentication C)
2017-03-06 15:35:56.969 DEBUG Pop3(1)[3] Info: State changed from 'Ready' to 'Sending'.
2017-03-06 15:35:56.969 VERBOSE Pop3(1)[3] Info: Sent data:
 0000 |51-55-49-54-0D-0A                              | QUIT..
2017-03-06 15:35:56.969 INFO Pop3(1)[3] Command: QUIT
2017-03-06 15:35:56.969 DEBUG Pop3(1)[3] Info: State changed from 'Sending' to 'Reading'.
2017-03-06 15:35:56.970 VERBOSE Pop3(1)[3] Info: Received data:
 0000 |2B-4F-4B-20-50-4F-50-33 20-73-69-67-6E-69-6E-67| +OK POP3 signing
 0010 |20-6F-66-66-20-0D-0A                           |  off ..
2017-03-06 15:35:56.970 INFO Pop3(1)[3] Response: +OK POP3 signing off
2017-03-06 15:35:56.970 DEBUG Pop3(1)[3] Info: State changed from 'Reading' to 'Downloading'.
2017-03-06 15:35:56.971 DEBUG Pop3(1)[3] Info: State changed from 'Downloading' to 'Disconnected'.

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It seems that the server falsely claims it supports `APOP` feature: https://tools.ietf.org/html/rfc1939#page-15
To explicitly disable it, please set the `Pop3.Settings.DisableApopAuthentication` to `true`.

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In version 2017 R2, we added a workaround for Dualog server, which automaticaly disables APOP feature.