In an ideal world, emails will work flawlessly and you never have to pull your hair out.

Unfortunately, we live in an imperfect world, where mails bounce with weird errors such as “User unknown in local recipient table“.

What is this table? How do I fix it? Out of all people in the world, why should I get this error?

Here we’ll see the answer for all these questions.

At Bobcares, we help website owners to fix these email bounce errors as part of our Support Engineers services for Web Hosts.

We’ve seen broadly 3 causes for the error “User unknown in local recipient table“.

Today we’ll discuss each of these causes and how we fix them.

What causes “User unknown in local recipient table” error?

“User unknown in local recipient table” is a common error reported by mail servers like MailEnable, Postfix, MailPlus etc.

The exact bounce message would look like :

MailEnable: Message could not be delivered to some recipients.

The following recipient(s) could not be reached:[SMTP:Ben@mailserver.com]:

Remote SMTP Server Returned: 550 5.1.1 : Recipient address rejected: User unknown in local recipient table

 

This bounce shows that mail server rejected the mail as it could not find the email address Ben@mailserver.com within the server.

For any email to work, mail servers need to know the delivery path of the mail.

Email delivery path will be either Local (mailbox within the server) or Remote (mailbox outside server).

At times, mail server confuses with the mail delivery path of a domain and will try to find a mailbox for a remote email address within the server.

This confusion can happen due to various reasons. The major ones include:

 

1. Bad DNS records

The mail server looks up mail record (MX) of a domain in DNS records and then decides whether it is local or remote email address.

When this MX record is not set correctly, it affects the email path of the domain.

From our expertise in managing servers, we see that server can hold wrong DNS records for the domain mainly in scenarios like:

1. Domain was transferred to a different server, but DNS records were not removed from old server.
2. Changes in DNS records were not updated in server.

2. Bad Email routing

Mail servers also provide an option to specify the email path of a domain using an “Email routing” setting. This can be set as either local or remote.

Mails will be sent outside the server when the “Email routing” is set as Remote.

But there can be configuration errors in this setting as well.

For example, if a domain uses Google’s servers as MX record, but has email routing set to “local”, server tries to deliver mails locally.  But as there are no mailboxes within the server, it will end up in the error “User unknown in local recipient table”.

 

3. Bad mail server setup

Additionally, wrong mail server setup also can cause the “User unknown” email error.

In mail servers like Postfix, the decision to deliver mails within the server depends on a setting called ‘mydestination’ .

A sample setting in postfix server config file looks like :

mydestination = $mydomain, localhost.$mydomain, localhost

Here, any mails sent to the domains added in ‘mydestination’ setting are to be delivered within the server.

At times, we see that the domain associated with server name is wrongly added in ‘mydestination’ setting.

On a server srv1.xyz.com,  when xyz.com is added to ‘mydestination’ setting, mail server tries to deliver mails for Sarah@xyz.com within the server.

And when there is no exact mail address created on the server, mail bounces with error “User unknown in local recipient table”.

Now let us see how we can solve this error and send emails to the correct mailbox.

 

How to fix “User unknown in local recipient table” error?

To fix the email error “User unknown in local recipient table”, our Support Engineers primarily corrects the domain configuration on the server which includes:

1. Remove wrong entries from domain’s DNS.
2. Correct mail path for the domain depending on the MX record of the domain.

At times, even when the domain entries are correct, this error still remains. This shows that the problem lies with mail server configuration.

To solve the error in mail servers like Postfix, we adjust the mail server configuration entries like  mydestination to ensure that server handle mails only for intended domains.

In case of MailEnable server, we configure utilities such as MERoute which can force any mail to a remote server.

Thus after making these changes, a mail is correctly routed to its mailbox.

 

Conclusion

“User unknown in local recipient table” email error happens mainly due to wrong domain settings or improper mail server configuration. Today we’ve discussed the top 3 causes for the error and how our Support Engineers fix them.