Hello, I got a problem with a customer, they are hosting their own mail server, and emails sent to them from their website is not recieved. In ispconfig 2 it was quite easy to tell the system to use extern mail server, but how do it do it in ispconfig 3?
Its even easier to do this in ispconfig 3 Email and websites are separated in ispconfig 3, so just do not create this domain as email domain if it is external.
Try to send an email from their website while you watch the mail log file with: tail -f /var/log/mail.log to see if there are any errors. (the name of the mail log file might be different on your system, the above path is for debian and ubuntu).
Joomla witch was the CMS system, gave some problems also, all other Joomla pages have so far as I know not given any problems sending mails. I moved the site to my ispconfig 2 server, it seems to work.