Message not sent.
Requested action not taken: mailbox unavailable
Server replied: 550 Verification failed for <user@domain.com>
No Such User Here
Sender verify failed
This might be caused by incorrect permissions or ownership on the email accounts.
If you have a cpanel account, try to compare the permissions/ownership with other accounts on the same server. If you don’t have access to other accounts, or only have one account, you can try comparing settings to what I list below, but I don’t know for sure if they will work in every case:
root@host [/home/user]# ls -la
drwxr-x--- 3 user mail 4096 Jan 10 17:22 etc/
drwxr-x--x 11 user user 4096 Jan 5 13:18 mail/
root@host [/home/user/etc]# ls -la
-rw-r--r-- 1 user user 9 Jan 10 17:22 cacheid
-rw-r--r-- 1 user user 0 Apr 18 2012 ftpquota
drwxr-x--- 5 user mail 4096 Jun 8 00:57 domain.com/
[root@host /home/user/etc/domain.com]# ls -la
-rw-r----- 1 user mail 154 Mar 7 10:22 passwd
-rw-r----- 1 user mail 662 Mar 7 10:22 passwd,v
drwxr-x--- 2 user user 4096 Mar 7 17:17 \@pwcache/
-rw-r----- 1 user mail 33 Mar 7 10:22 quota
-rw-r----- 1 user mail 541 Mar 7 10:22 quota,v
-rw-r----- 1 user user 249 Mar 7 10:22 shadow
-rw-r----- 1 user user 1031 Mar 7 10:22 shadow,v
root@host [/home/user/mail]# ls -la
lrwxrwxrwx 1 user user 22 Mar 6 09:28 .admin\@domain_com -> domain.com/admin/
lrwxrwxrwx 1 user user 22 Mar 6 09:28 .test\@domain_com -> domain.com/test/
drwxr-x--x 2 user user 4096 Feb 23 2014 courierimapkeywords/
-rw-r----- 1 user user 47 Feb 12 2015 courierimapsubscribed
-rw-r--r-- 1 user user 124 Feb 23 2014 courierimapuiddb
drwxr-x--x 2 user user 4096 Feb 12 2015 cur/
-rw-r--r-- 1 user user 128 Jan 5 13:18 dovecot-uidlist
drwxr-x--x 6 user user 4096 Feb 12 2015 .Drafts/
drwxr-x--x 6 user user 4096 Jan 5 13:18 .Junk/
-rw-rw---- 1 user user 26 Jan 31 2013 maildirsize
drwxr-x--x 2 user user 4096 Feb 23 2014 new/
drwxr-x--x 6 user user 4096 Feb 12 2015 .Sent/
-rw-r--r-- 1 user user 23 Jan 5 13:18 subscriptions
drwxr-x--x 2 user user 4096 Aug 9 2015 tmp/
drwxr-x--x 6 user user 4096 Feb 23 2014 .Trash/
drwxr-x--x 4 user user 4096 Apr 12 2013 domain.com/
root@host [/home/user/mail/domain.com]# ls -la
drwxr-x--x 10 user user 4096 May 16 17:46 admin/
drwxr-x--x 10 user user 4096 Jun 7 17:21 test/
root@host [/home/user/mail/domain.com/admin]# ls -la
total 76
drwxr-x--x 10 user user 4096 May 16 17:46 ./
drwxr-x--x 4 user user 4096 Apr 12 2013 ../
-rw-r----- 1 user user 43 Feb 12 2015 courierimapacl
drwxr-x--x 2 user user 4096 Jun 2 2015 courierimapkeywords/
-rw-r----- 1 user user 36 Jun 2 2015 courierimapsubscribed
-rw-r--r-- 1 user user 14 Jun 2 2015 courierimapuiddb
drwxr-x--x 2 user user 4096 Dec 11 2012 cur/
-rw-r----- 1 user user 0 May 16 17:46 dovecot-acl-list
-rw-r----- 1 user user 168 May 16 17:46 dovecot.index.log
-rw-r----- 1 user user 24 May 16 17:46 dovecot.mailbox.log
-rw-r----- 1 user user 50 May 16 17:46 dovecot-uidlist
-rw-r----- 1 user user 8 May 16 17:46 dovecot-uidvalidity
-r--r--r-- 1 user user 0 May 16 17:46 dovecot-uidvalidity.573a3fd6
drwxr-x--x 5 user user 4096 May 16 17:46 .Drafts/
drwxr-x--x 5 user user 4096 May 16 17:46 .Junk/
-rw-r----- 1 user mail 14 Dec 11 2012 maildirsize
drwxr-x--x 2 user user 4096 Dec 11 2012 new/
drwxr-x--x 5 user user 4096 May 16 17:46 .Sent/
-rw-r----- 1 user user 23 May 16 17:46 subscriptions
drwxr-x--x 2 user user 4096 Jun 2 2015 tmp/
drwxr-x--x 6 user user 4096 May 16 17:46 .Trash/
Then for emails themselves, like the ones in cur, new, .Sent, and any other mailbox folders, the email should have permissions/ownership like this:
-rw-r----- 1 user user 6132 May 2 17:33 1462224789.H590338P32071.host.domain.com,S\=6132:2,RS
If you are getting other “Server replied: 550 Verification failed for” errors, try these links possibly if your error matches:
Connection rejected: SPAM source domain.com is manually blacklisted.
No Such User Here
The mail server could not deliver mail to user@domain.com. The account or domain may not exist, they may be blacklisted, or missing the proper dns entries.