Technical Diary - With Andrii Grytsenko

Command list of IMAP and POP3 protocols. They can be used to test your server remotely over telnet connection.

Assume you set up pop3 and imap and want to check it out.

POP3
POP3 is quite simple protocol. I think you will make out how it’s work without any problem.

First, let’s go to check the POP3 server. Make sure that it bound at port 110:

# netstat -lnp | grep 110
tcp        0      0 0.0.0.0:110                 0.0.0.0:*                   LISTEN      2779/dovecot

As you can see I use dovecot as server application and it’s works on all interfaces.
Next, make connection attempt:

# telnet 127.0.0.1 110
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
+OK Dovecot ready.

Now, we got server answer. Do authorization with command user and pass

USER user1
+OK
PASS qwe
+OK Logged in.

and LIST to see headers of all inbox mails:

LIST
+OK 1 messages:
1 306
.

We have only one mail. First field of answer means

mail_id

.
To see whole mail use RETR mail_id:

RETR 1
+OK 306 octets
Return-Path: 
Received: from d (node1 [10.0.30.1])
        by mail.test.com (8.13.8/8.13.8) with SMTP id n8ONtVLG011279
        for user1@test.com; Fri, 25 Sep 2009 03:04:08 +0300
Date: Fri, 25 Sep 2009 03:04:08 +0300
From: fd@test.com
Message-Id: <200909250004.n8ONtVLG011279@mail.test.com>
test

To delete it:

DELE 1
+OK Marked to be deleted.

This message marked as deleted and will be removed when you send command QUIT to server. To unmark messages use command RSET without any arguments:

RSET
+OK

Use command QUIT to leave the server.

QUIT
+OK Logging out.

Refer to RFC 1939 for more details.

IMAP
By default IMAP listen port 143. Therefore let’s check it first:

# netstat -lnp | grep 143
tcp        0      0 0.0.0.0:143                 0.0.0.0:*                   LISTEN      2779/dovecot

Try to connect:

# telnet localhost 143
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
* OK Dovecot ready.

Okay, we have got good answer. Now, we should authorize on server. Syntax is:
? LOGIN USER/ALIAS PASSWORD

For example:

? login user1 qwe
? OK Logged in.

To get folders list make:

? LIST "" "*"
* LIST (\NoInferiors \UnMarked) "/" "INBOX"
? OK List completed.

In folder INBOX contain all incoming messages. To select it:

? SELECT INBOX
* FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
* OK [PERMANENTFLAGS (\Answered \Flagged \Deleted \Seen \Draft \*)] Flags permitted.
* 1 EXISTS
* 0 RECENT
* OK [UNSEEN 1] First unseen.
* OK [UIDVALIDITY 1253837819] UIDs valid
* OK [UIDNEXT 2] Predicted next UID
? OK [READ-WRITE] Select completed.

1 EXISTS – means 1 incoming message. You can choose between see full message or only message body instead:
? FETCH message_number All
OR
? FETCH message_number Body

Let’s see whole message:

? FETCH 1 all
* 1 FETCH (FLAGS () INTERNALDATE "25-Sep-2009 03:04:12 +0300" RFC822.SIZE 306 ENVELOPE ("Fri, 25 Sep 2009 03:04:08 +0300" NIL ((NIL NIL "fd" "test.com")) ((NIL NIL "fd" "test.com")) ((NIL NIL "fd" "test.com")) NIL NIL NIL NIL "<200909250004.n8ONtVLG011279@mail.test.com>"))
? OK Fetch completed.

Exit user command is ? LOGOUT.

To learn more about IMAP refer to RFC 3501.