If you are getting an error while sending mails using the webmail client ‘Squirrel mail’;
Server replied: 451 Temporary local problem – please try later.
SOLUTION
This error is due to the missing entry of the recipient domain in ‘/etc/localdomains’.
$ vi /etc/localdomains ( Add the domain name in this file)
Then restart the Exim service.
$ /etc/init.d/exim restart
This should fix the error.
NOTE : If you upgraded exim recently, then you should restore the localdomains in order to update the changes.
$ cd /etc/
$ ls -al localdomains.eximreset
$ cp localdomains.eximreset localdomains
$ ls -al localdomains.eximreset
$ cp localdomains.eximreset localdomains
Now add the domain name and restart the mail service.