What do the SMTP error / reply codes mean?

The AuthSMTP SMTP mail server service is designed to solve many of the problems people have when sending Internet email and is compatible with almost all current email client and server software.

If you do not already have an AuthSMTP account click here or review the features, benefits and low cost .

Here is a reference table of SMTP error / reply codes and a brief description of their meaning:

211System status or system help reply.
214Help message.
220Domain service ready - ready to start TLS.
221Domain service closing transmission channel.
250OK - queuing for node started - requested mail action okay, completed.
251OK - no messages waiting for node - user not local will forward to forward path.
252OK - pending messages for node started - cannot VRFY user but will accept message and attempt delivery.
253OK - messages pending - messages for node started.
354Start mail input - end with ..
355Octet-offset is the transaction offset.
421Domain service not available - closing transmission channel.
432A password transition is needed.
450Requested mail action not taken: mailbox unavailable - ATRN request refused.
451Requested action aborted - local error in processing - unable to process ATRN request.
452Requested action not taken - insufficient system storage.
453You have no mail.
454TLS not available due to temporary reason - encryption is required for requested authentication mechanism.
458Unable to queue messages for node
459Node not allowed: reason.
500Command not recognized 'command' - syntax error.
501Syntax error - no parameters allowed.
502Command not implemented.
503Bad sequence of commands.
504Command parameter not implemented.
521Machine does not accept mail.
530Must issue a STARTTLS command first - encryption required for requested authentication mechanism.
534Authentication mechanism is too weak.
538Encryption required for requested authentication mechanism.
550Requested action not taken - mailbox unavailable.
551User not local - please try forward path.
552Requested mail action aborted - exceeded storage allocation.
553Requested action not taken - mailbox name not allowed.
554Transaction failed.

If you have any questions please contact us.