×
×

SMTP Reason / Rejection Codes

Back

101

The server is unable to connect

111

Connection refused or inability to open an SMTP stream

211

System status message or help reply

214

A response to the HELP command

220

The server is ready

221

The server is closing its transmission channel, It can come with side messages like "Goodbye" or "Closing connection"

250

Its typical side message is "Requested mail action okay completed": meaning that the server has transmitted a message

251

"User not local will forward": the recipient's account is not on the present server, so it will be relayed to another

252

The server cannot verify the user, but it will try to deliver the message anyway

354

The side message can be very cryptic ("Start mail input end ."), It's the typical response to the DATA command

420

"Timeout connection problem": there have been issues during the message transfer

421

The service is unavailable due to a connection problem: it may refer to an exceeded limit of simultaneous connections, or a more general temporary problem

422

The recipient's mailbox has exceeded its storage limit

431

Not enough space on the disk, or an "out of memory" condition due to a file overload

432

Typical side-message: "The recipient's Exchange Server incoming mail queue has been stopped"

441

The recipient's server is not responding

442

The connection was dropped during the transmission

446

The maximum hop count was exceeded for the message: an internal loop has occurred

447

Your outgoing message timed out because of issues concerning the incoming server

449

A routing error

450

"Requested action not taken – The user's mailbox is unavailable", The mailbox has been corrupted or placed on an offline server, or your email hasn't been accepted for IP problems or blacklisting

451

"Requested action aborted – Local error in processing", Your ISP's server or the server that got a first relay from yours has encountered a connection problem

452

Too many emails sent or too many recipients: more in general, a server storage limit exceeded

471

An error of your mail server, often due to an issue of the local anti-spam filter

500

A syntax error: the server couldn't recognize the command

501

Another syntax error, not in the command but in its parameters or arguments

502

The command is not implemented

503

The server has encountered a bad sequence of commands, or it requires an authentication

504

A command parameter is not implemented, Bad email address, Bad email address, A DNS error: the host server for the recipient's domain name cannot be found

513

"Address type is incorrect": another problem concerning address misspelling, In few cases, however, it's related to an authentication issue

523

The total size of your mailing exceeds the recipient server's limits

530

Normally, an authentication problem, But sometimes it's about the recipient's server blacklisting yours, or an invalid email address

541

The recipient address rejected your message: normally, it's an error caused by an anti-spam filter

550

It usually defines a non-existent email address on the remote side

551

"User not local or invalid address – Relay denied", 
Meaning, if both your address and the recipient's are not locally hosted by the server, a relay can be interrupted, 552 "Requested mail actions aborted – Exceeded storage allocation": simply put, the recipient's mailbox has exceeded its limits

553

"Requested action not taken – Mailbox name invalid", That is, there's an incorrect email address into the recipients line

554

This means that the transaction has failed, It's a permanent error and the server will not try to send the message again.