SMTP Error Messages

SMTP Response Codes and Errors

Explore our Newsletter Software Arclab® MailList Controller

Arclab® MailList Controller is the complete solution for newsletter mailings and email marketing campaigns. Test drive our software or use the free version as long as you want. There is no registration required.

Learn more

Simple Mail Transfer Protocol (SMTP) is an internet standard for email transmission.
SMTP is a text based protocol in which the sender communicates with the mail receiver by issuing comands and receiving a response code.

 

Sample:

C: MAIL FROM:<someone@arclab.com>
S: 250 Ok

In this sample the client issues the MAIL FROM command and the server replies with 250 Ok.

 


 

The following list of response codes and error messages should help you to find errors in your settings.

 

 

SMTP Error 221

221 <domain> Service closing transmission channel
221 Closing transmission
221 Goodbye

221 is an authentication error. It means you are using the wrong mail server, the user/password is incorrect or you need to change the authentication method. Try SSL/StartTLS if you are sure that the mail server and user/password is correct.

 

SMTP Error 451

451 Requested action aborted: local error in processing
451 You have exceeded your messaging limits

The program cannot send more messages, because your mail account (or mail server) has a limitation.
Some mail server have limits, e.g. some allow to send a max. number of x messages per hour, others use a daily limit.
Please contact your mail administrator (mail provider) regarding this issue or wait some time before sending further messages.

If you are using MailList Controller then you can use the "List Settings" > "Outgoing Messages (SMTP)" > "Limit" feature to adjust the program to such a limit. The mailing will stop after the limit was reached and continues after the specified amount of time.

 

SMTP Error 530

530 5.7.0 Must issue a STARTTLS command first

Use StartTLS (or TLS) as authentication method (encryption) in the settings of your mail account.

 

SMTP Error 550

550 Requested action not taken: mailbox unavailable [E.g., mailbox not found, no access]
550 5.7.1 unable to relay for

You will get this error when you try to send an email to an invalid email address or if you need to authenticate before sending an email.  Try switching to SSL/TLS in the mail account settings of the client to resolve this error.

 

SMTP Error 553

553 Requested action not taken: mailbox name not allowed (e.g. mailbox syntax incorrect)
553 Sorry, over your daily relay limit

The program cannot send more messages, because your mail account (or mail server) has a limitation.
Some mail server have limits, e.g. some allow to send a max. number of x messages per hour, others use a daily limit.
Please contact your mail administrator (mail provider) regarding this issue or wait some time before sending further messages.

If you are using MailList Controller then you can use the "List Settings" > "Outgoing Messages (SMTP)" > "Limit" feature to adjust the program to such a limit. The mailing will stop after the limit was reached and continues after the specified amount of time.

Disclaimer: The information on this page is provided "as is" without warranty of any kind. Further, Arclab Software does not warrant, guarantee, or make any representations regarding the use, or the results of use, in terms of correctness, accuracy, reliability, currentness, or otherwise. See: License Agreement