Are your emails from WHMCS failing ? Does it reach your clients at times and fails often ?
Start by checking for the activity logs under – Utilities -> Logs.
If you find this error message :
“It failed with this message – Email Sending Failed – SMTP connect() failed”.
It means that the SMTP connection isnt reaching the destination mail host.Enable the Email debug and check for more details.
If you find something like this -_php_network_getaddresses:_getaddrinfo_failed:_Name_or_service_not_known
It has to be an issue with the DNS resolvers. At times, the mail may go out and at times, it would get stalled.
Adding Google’s Public DNS to your resolver config should solve this issue.
Facing any further issues in WHMCS email delivery ? Get in touch with us at K9 Webops