What are the SMTP commands?
What are the five mandatory commands used in SMTP?
- HELO. It’s the first SMTP command: is starts the conversation identifying the sender server and is generally followed by its domain name.
- EHLO. An alternative command to start the conversation, underlying that the server is using the Extended SMTP protocol.
- MAIL FROM.
- RCPT TO.
What is SMTP response?
An SMTP response code is a three digit code that the servers use to communicate throughout the email sending process. This response code can be good, like 250 (The requested action was taken) or it can indicate an that there was a communication error.
Which command initiates the SMTP conversation?
The HELO command
The HELO command initiates the SMTP session conversation. The client greets the server and introduces itself. As a rule, HELO is attributed with an argument that specifies the domain name or IP address of the SMTP client.
What is SMTP Rcpt?
RCPT TO. The RCPT TO command specifies the recipient. As an argument, RCPT TO includes a destination mailbox (forward-path). In case of multiple recipients, RCPT TO will be used to specify each recipient separately.
What are Vrfy and Expn requests?
A VRFY request asks the server to verify an address. Its parameter may be an encoded address or a user name in a server-defined format. If the server accepts the request (required code 250, 251, or 252), it may provide information about the address in a server-defined format.
What does 250 mean?
A server response of “250 OK” indicates that the SMTP communication was successful and it’s issued in response to every accepted command — likely 4 to 6 times per message.
What is the meaning of 221 response code in SMTP *?
Error 221 is an authentication error, which means you are using the wrong mail server, the user/password is incorrect, you need to change the authentication method or SMTP access is not enabled for your email account. Try using SSL/TLS if you are sure that the mail server and user/password is correct.
Why is SMTP Ehlo?
Answer. The SMTP HELO clause is the stage of the SMTP protocol where a SMTP server introduce them selves to each other. The sending server will identify who it is and the receiving server will (as per RFC) accept any given name. There is no requirement to give the correct information at this stage.