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SMTP and POP3 commands
SMTP and POP3 are the components used to send and receive email. These tables include the actual commands used by email clients.
A great way to verify an email server is to manually execute the SMTP and POP3 commands directly from the command line by typing in the following:
telnet <mail server name/IP address> <port#>
Outgoing email (SMTP) uses port #25
Incoming email (POP3) uses port #110.
| Command | Comment |
|---|---|
| USER <name> | Your user name for this mail server |
| PASS <password> | Your password. |
| QUIT | End your session. |
| STAT | Number and total size of all messages |
| LIST <message#> | Message# and size of message |
| RETR message# | Retrieve selected message |
| DELE message# | Delete selected message |
| NOOP | No-op. Keeps you connection open. |
| RSET | Reset the mailbox. Undelete deleted messages. |
Normal program flow:
USER <name>
PASS <password>
LIST
DELE <selected messages>
QUIT
Accessing your pop3 server manually is useful when a corrupted message is causing your incoming email to abort. This results in the same message being sent over and over. The best way to solve this problem is to telnet into your email server, delete all messages already received and the offending message.
The backspace
is not a key to press when running SMTP/POP3 manually.
Only one person can access the mailbox at any time.
| Command | Comment |
|---|---|
| ATRN | Authenticated TURN |
| AUTH | Authentication |
| BDAT | Binary data |
| BURL | Remote content |
| DATA | The actual email message to be sent This command is terminated with a line that contains only a <period><return> |
| EHLO | Extended HELO |
| ETRN | Extended turn |
| EXPN | Expand |
| HELO | Identify yourself to the SMTP server. |
| HELP | Show available commands |
| Send mail from email account MAIL FROM: me@mydomain.com |
|
| NOOP | No-op. Keeps you connection open. |
| ONEX | One message transaction only |
| QUIT | End session |
| RCPT | Send email to recipient RCPT TO: you@yourdomain.com |
| RSET | Reset |
| SAML | Send and mail |
| SEND | Send |
| SOML | Send or mail |
| STARTTLS | |
| SUBMITTER | SMTP responsible submitter |
| TURN | Turn |
| VERB | Verbose |
| VRFY | Verify |
The following is an actual SMTP session. All sessions must start with HELO and end with QUIT.
HELO my.server.com
MAIL FROM: <danny@mydomain.com>
RCPT TO: <sarah@yourdomain.com>
DATA
From: Danny Dolittle <danny@mydomain.com>
To: Sarah Smith <sarah@yourdomain.com>
Subject: Email sample
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
This is a test email for you to read.
.
QUIT