354

SMTP Code 354: Start Mail Input

Informational Low severity Protocol RFC 5321
What it means

SMTP Code 354 means “Start Mail Input.” The server is ready to receive the message body. This is the normal response after the DATA command, indicating you can begin transmitting the email content (headers and body).

At a glance
Code354
Bounce typeNot a bounce
SeverityLow
CategoryProtocol
What to doNone; informational status
StandardRFC 5321
What it looks like in your mail logs 
354 Go ahead, end your data with <CR><LF>.<CR><LF> d75a77b69052e-46c1c0a2f9bsi - gsmtp

What does 354 mean?

SMTP code 354 is the server's response to the DATA command, indicating it is ready to receive the actual email content including headers and body. The sending server should then transmit the message, ending with a line containing only a period (.) to signal the end of the message.

This is a standard part of every SMTP transaction and is not a bounce code. If your server is not receiving a 354 after sending DATA, it typically means the server rejected the transaction earlier (invalid sender or recipient) or there is a protocol-level issue with the SMTP conversation.

How 354 plays out

Your server and the recipient exchange SMTP commands
The recipient returns 354 as a status reply
No delivery failure; this code is informational

Common causes of 354

  • Normal SMTP flow - server is ready to receive message content
  • DATA command was accepted after valid MAIL FROM and RCPT TO

How to fix 354

  • No fix needed - this is a standard SMTP response
  • If not receiving 354 after DATA, check previous SMTP responses for errors
  • Ensure MAIL FROM and RCPT TO were accepted (250) before sending DATA

Frequently asked questions

What does SMTP 354 "Start mail input" mean?
SMTP 354 means the server has accepted your sender and recipient information and is now ready to receive the email message body. It is a positive intermediate response issued after the DATA command, signaling that you should begin transmitting the email content. The message body must be terminated with a line containing only a single period (.) to signal the end of transmission.
Is SMTP 354 an error?
No, SMTP 354 is not an error. It is a normal part of the SMTP conversation indicating the server is ready to accept the email body content. According to RFC specifications, 354 is classified as a positive intermediate reply. If your email client logs it as an error, the issue lies with the client software, not the mail server.
Why does my email get stuck after SMTP 354?
If email transmission stalls after receiving a 354 response, the sending application is likely failing to transmit the message body or the termination sequence. Ensure your email client sends the complete message body followed by the CRLF.CRLF termination sequence (a period on a line by itself). Also check for firewall interference on ports 25/587 and network connectivity issues that could interrupt the data transfer.

Related bounce codes

250 Requested Action Completed 500 Syntax Error - Command Unrecognized 503 Bad Sequence of Commands

Sources & further reading

RFC 5321 · The standard that defines this reply code RFC 5321 section 4.1.1.4 · The DATA command and the 354 intermediate reply that starts message input
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026 ← All bounce codes