SMTP Protocol |
index |
| SMTP Commands and Meanings | SMTP Messages | ETRN Transactions | For More Information |
| Command Name | Definition | Description | Status |
|---|---|---|---|
| HELO | Introduction | ||
| EHLO | Introduction (extended SMTP mode) | ||
| RSET | System Reset | ||
| EXPN | Expand Mailing List | SMTP server returns address of final destination for any mail addressed to the specified address. | Often disabled due to security risks. This command allows potential spammers to determine which addresses are valid on this host. |
| NOOP | No Operation | A null command. Does nothing. | |
| VERB | Verbose mode | Server responds to message send with a much more verbose, but non-standard, status dialogue. | |
| Specify Mail Sender | |||
| TURN | Mail Turn | SMTP server begins dequeueing queued mail for the specified domain to the host which opened the current SMTP session. | Usually disabled due to risk of dequeueing mail to an unauthorized host. See ETRN. |
| ETRN | Extended Turn | SMTP server looks up the primary MX record for the domain specified and begins dequeueing all queued mail to that host. | Preferred instead of TURN. Not available on all SMTP implementations. |
| RCPT | Specify Mail Recipient | ||
| HELP | |||
| DATA | Specify Message Content | ||
| VRFY | Verify Address | SMTP server acknowledges whether specified address is valid. | Often disabled for security to avoid helping potential spammers generate address lists. |
| DSN | Delivery Status Notifications | ||
| QUIT | Quit | End SMTP Session |
| Example | Description |
|---|---|
EHLO sender's domain
MAIL FROM: sender address [RET={FULL | HDRS}] [ENVID=envid]
RCPT TO: recipient address [NOTIFY={NEVER,SUCCESS,FAILURE,DELAY}]
[ORCPT=recipient]
DATA
From: sender name <sender address>
To: recipient name <recipient address>
Subject: subject
Date: date
message body here
.
|
RET (specify whether to return full message or headers in case of failure ORCPT (specify receipt recipient) Optional. If omitted, defaults to sender specified above To, Subject, and Date also optional. End with a single period on a line by itself. |