cPanel provides three standard webmail applications, namely Horde, Roundcube, and SquirrelMail. I would like to explain two errors which we face during sending mails from the Email web interface applications and the solution to fix the errors.

1 Roundcube Webmail “An error occurred”

If you came around the error “Unexpected condition from IMAP server, closed or corrupt connection to IMAP. Possible mailbox corruption”.
First of all access the Roundcube errorlog at: tail ­f /var/cpanel/roundcube/log/errors and check the following error entry will be possibly displayed in error logs.

Unexpected condition from IMAP server, closed or corrupt connection to IMAP. Possible mailbox corruption.

From the error, we can assume that the index file is corrupted. Solution

Every mailbox has its own separate index files. TheDovecotindex file is created to read the mailboxes faster. If index files are removed, thenDovecotcreates the file automatically when the mailbox is opened.

Go to the path

/home/<username>/mail/<domain name>/<email account name>/

Finddovecot.index and rename it todovecot.index.back

#mvdovecot.indexdovecot.index.back

Log into Roundcube webmail and the error should no longer appear (as a newdovecot.index file is generated upon login).

2 There was an error sending your message: Failed to add recipient: xxxxxx@gmail.com [SMTP: Invalid response code received from server (code: 451, response: Temporary local problem ­ please try later)]

When you try to send Emails via any cPanel, webmail clients is, Horde, Roundcube, and SquirrelMail and when you come across the following error in a warning box.

There was an error sending your message: Failed to add recipient: xxxxxx@gmail.com [SMTP: Invalid response code received from server (code: 451, response: Temporary local problem ­ please try later)]

This error message shows that the particular domain name is not present in the file /etc/localdomains.

Solution

The solution is simple, If you have access to shell open the /etc/localdomains with your favorite text editor and then include the domain name having the error and save.

# vi/etc/localdomains
# insert the domain name
# save the file
# /etc/init.d/exim restart
Now you can send the Emails without any error warnings.