I'm trying to send an email establishing a telnet connection with the smtp server. I succeed to establish the connection with the port 587, the authentication works, I enter the mail from: <>, the rcpt to:<> and it works.

Finally, when I type the data, enter the dot and type enter, I receive a message saying :

550 5.5.0 Service refuse. Service refused, please try later. LPN105_510

I'm trying to understand why it doesn't accept to send my email. I tried by establishing a TLS connection, it didn't work. I'm thinking it might be because of the "domain" I'm giving after the ehlo (localhost), but I have read that it was not important. If it was because of my IP address, I would not be allowed to get so far (connection + authentication). My ATM would do exactly the same operation, right ?

I really don't see what it can be. Here is the connection sequence :

Connected to smtp.laposte.net.
Escape character is '^]'.
220 lpn-prd-vrin003 ESMTP Postfix (Ubuntu)
ehlo localhost
250-SIZE 26214400
250 DSN
auth login
334 VXNlcm5hbWU6
334 UGFzc3dvcmQ6
235 2.7.0 Authentication successful
mail from: <xxxxxxxxxxxx@laposte.net>
250 2.1.0 Ok
rcpt to: <xxxxxxxxxxx@gmail.com>
250 2.1.5 Ok
354 End data with <CR><LF>.<CR><LF>
550 5.5.0 Service refuse ,service refused, 
please try later. 

There can be a number of reasons why your mail gets rejected. However, the rejection message (Service refuse ,service refused, please try later.) is not standard and seems to be added as a restriction by the mail server administrator.

In case of Postfix, this can happen for lots of reasons:

  • The sender address cannot send e-mails from this domain.
  • The recipient address cannot receive e-mails from this domain.
  • Although localhost is accepted as a EHLO FQDN in the RFC, the server admin could explicitly reject it.
  • The message body contains an unwanted string.
  • The message was filtered by a milter and determined that (for some reason) it shouldn't be sent.
  • ...

The only way to determine the reason is asking the e-mail administrator and ask them why are you getting the message rejected. If you're the administrator, please, post Postfix logs (/var/log/mail.log).


This is a known problem with laposte.net. Maybe they have a crazy anti-spam software.

The google search of 550 Service refused laposte.net returns more than 4000 such discussions, so the problem is better addressed to their website.

You could of course use another mail furnisher, such as gmail.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.