What the ‘SMTP Error from Remote Mail Server after RCPT TO’ Error Occurs? 5 Potential Reasons

What the ‘SMTP Error from Remote Mail Server after RCPT TO’ Error Occurs? 5 Potential Reasons

Email errors are common and can be really bothersome. One email error that creates havoc for admins is the ‘SMTP Error from Remote Mail Server after RCPT TO’ error. It pops up when you send emails from one account to another. But why does this crop up and how to fix it? Check out in this article.

What is this error?

At first sight, the error message gives very little hint as to what the actual reason is behind it. Therefore, it gets even more confusing.

For the uninitiated, the RCPT command informs the mail server of the sender who the recipient of the email is. From the error message, you can make a guess that perhaps its this command where the operation failed and you got this error.

But to get to the core reason, you need to inspect and dissect the entire bounce message.

Reasons Behind the ‘SMTP Error from Remote Mail Server after RCPT TO’ error?

There are different reasons behind the RCPT error. Here are the five most common reasons:

Configuration Errors

If you receive the following bounce message, then it’s most likely because of configuration issues:

SMTP error from remote mail server after RCPT TO:<user@domain.com>: host domain.com [xx.xx.xx.xx]: 550-Please turn on SMTP Authentication in your mail client. 550-(host.domain.com) [yy.yy.yy.yy]: __ is not permitted to relay through this server without authentication.

When you send emails from an account with incorrect configuration, the mail server will throw an error. Furthermore, you may also get the error when there are any mail server configuration issue.

To fix this issue, you need to fix the configuration errors. Ensure that you have correct SMTP server and port number along with proper mail account details in place.

For PHP mail forms, you need to start using SMTP authentication if you haven’t already.

Furthermore, it’s advised that you duly check the MX records and relevant configuration files to fix any configuration issue.

Domain Blacklisting

Mail servers use RBLs or blacklist providers to prevent spam. When the RBLs label your mail server as spam origin, then you’ll get the following error message:

Code:
SMTP error from remote mail server after RCPT TO:<user@domain.com>: host domain.com [xx.xx.xx.xx]: 550-"JunkMail rejected - host.domain.com [yy.yy.yy.yy]: ___ is in an RBL, see http://www.spamhaus.org/query/bl?ip=________
When you get this message, you should check if anyone is sending bulk spam emails from your mail server.

But to fix this issue, you need to de-list your mail server from the spam origin list of RBL. This is going to be a time-consuming process.

You need to contact the RBL and explain why your server might have been labeled as spam. Also, assure them that you’ve taken necessary steps to resolve the problem. The final decision will be at the RBL’s discretion. But they’ll most likely help you out with de-listing your mail server.

To avoid getting into such mess, it’s recommended to proactively check for potential misuse of your email server and keep it secure.

rDNS Misconfiguration

The problem might also lie in the rDNS or Reverse DNS lookup. If that’s the case, you’ll get the following error message:

Code:
SMTP error from remote mail server after RCPT TO:<user@domain.com>:
host mx.domain.com [xx.xx.xx.xx]: 554 5.7.1 <unknown[yy.yy.yy.yy]>:
Client host rejected: envelope policy RBL PTRNUL
The rDNS has pointers which are intended to map the IP to a hostname, which helps validate the server. But if there is a misconfigured rDNS or no RDNS at all, the recipient’s server may reject incoming emails.

The solution to this is setting up an rDNS file if it’s missing. Or fix the issues that might be associated with it. Along with that, you should also configure other mail records like SPF and DKIM.

Error on Recipient Side

At times, the issue might be on the recipient side. If that’s the case, here are the error message you’re likely to get:

Code:
SMTP error from remote mail server after RCPT TO:
<user@domain.com>: 552 5.1.1 <user@domain.com>
Mailbox delivery failure policy error
SMTP error from remote mail server after RCPT TO:
550 5.1.1 xxxxxxxx Recipient Suspended (TT999)

SMTP error from remote mail server after RCPT TO:<user@domain.com>: 550 5.1.1 <user@domain.com> Recipient not found.

If the server account doesn’t exist or there are issues with their MX records, then the email delivery will fail.

The only way to resolve this issue is to contact the recipient and inform him/her about the problem. After they take the necessary steps, you should be able to send emails as usual.

Issues on Sender side

Similarly, there might be issues on the sender side other than the ones mentioned above. In such cases, here are the messages you’re likely to get:

Code:
SMTP error from remote mail server after RCPT TO:<user@domain.com>:
host host.domain.com [xx.xx.xx.xx]: 554 5.1.8 <user1@domain1.com>:
Sender address rejected: Domain not found
SMTP error from remote mail server after RCPT TO:<user2@domain2.com>:
host mx.server.com [xxx.xxx.xxx.xxx]: 550-Verification failed for <user1@domain1.com>
550-No Such User Here : Sender verify failed

There can be many issues on the sender’s side. Some of the most common ones are:
  • There are duplicate sender accounts in the recipient’s server
  • The mail configuration is not configured properly
  • The email account for the sender doesn’t exist or isn’t available at the moment
  • There’s lack of permission (it may happen after migration or server updates)
The error message you get should make it clear. So check the mail server logs and pinpoint the issue.

Then take necessary measures to fix the problem at hand. If you’re successful, the emails delivery should work as intended.

So this is how you deal with the ‘SMTP Error from Remote Mail Server after RCPT TO’ error. For more assistance, contact the email hosting support team.
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