Symptoms
Being unable to send or receive mail and receiving errors like the following in the exim error log:
2015-03-05 11:43:41 fixed_login authenticator failed for (ispip.net) ([XX.XX.XX.XX]) [YY.YY.YY.YY]: 535 Incorrect authentication data (set_id=user@domain.tld)
Troubleshooting
There are a number of reasons this issue may occur which differ depending on how many accounts are being impacted:
- One email account on one domain on a cPanel account
- All email accounts on one cPanel account
- All email accounts on all cPanel accounts
Knowing which is impacted helps to narrow down substantially where the issue is occurring:
[Impacted - one email account on one domain on a cPanel account]
Could be caused by incorrect permissions (ownership or file) on /home/username/mail/domain.com/passwd, shadow or quota file permissions
Could be caused by missing user /home/username/mail/domain.com/passwd, shadow or quota file(s)
Could be caused by incorrect permissions (ownership or file) on /home/username/mail/domain.com/emailuser folder or subfolder (cur, new)
Could be caused by missing /home/username/mail/domain.com/emailuser folder or subfolder (cur, new)
[Impacted - all email accounts on one cPanel account]
Could be caused by incorrect permissions (ownership or file) on any level leading up to /home/username/mail/domain.com/passwd, shadow or quota file(s)
Could be caused by missing users in /home/username/mail/domain.com/passwd, shadow or quota file(s)
Could be caused by setting immutable attributes on /home/username/mail/domain.com/passwd, shadow or quota file(s)
Could be caused by incorrect permissions (ownership or file) on any folders leading up to /home/username/mail/domain.com
Could be caused by missing /home/username/mail or /home/username/mail/domain.com folders
Could be caused by domain not being properly owned (/scripts/whoowns domain.com)
Could be caused by account not having been properly unsuspended (grep -i suspend /var/cpanel/users/username)
Could be caused by domain not digging to the machine for the DNS zone
Could be caused by the domain not being in /etc/localdomains and/or in /etc/remotedomains
[Impacted - all email accounts on all cPanel accounts]
Could be caused by exim not running
Could be caused by CSF firewall or iptables blocking port incoming and/or outgoing 25
Could be caused by immutable attribute set on /etc/exim.conf or any exim file(s) needing to be updated
Could be caused by Perl module issues
Could be caused by domains being in /etc/remotedomains
Could be caused by resolver not working (/etc/resolv.conf)
Could be caused by bind not properly working for named resolving local domains
Be aware that this is not a complete list of the possible issues that may cause the "535 Incorrect authentication data" error.
If you require additional assistance, feel free to contact cPanel Technical Support.