I'm a newcoming user of XFileSharingPro, or recently moved my main server from one to another.
Now I have mentioned that many of my users are not receiving my site's e-mails for some reasons. What's the problem and how could I fix that?
You have to fix a reverse DNS zone corresponding to your new main server's IP.
Reverse DNS zone checking tool: http://mxtoolbox.com/ReverseLookup.aspx (results should be looking exactly as 'yourdomain.com.').
What is a "reverse DNS zone": https://en.wikipedia.org/wiki/Reverse_DNS_lookup
Q: I have found that my reverse DNS zone is wrong by using that tool. How can I set it to "mydomain.com."?
A: In most of cases it's possible to do that in your hoster's web interface. If you haven't found anything like that in your hoster's web interface, you have to contact your hoster's support about that because nobody else can do that for you.
Q: I have a root password, is it enough to fix that?
A: No, it's only possible to do that through your hoster's web interface (if he allows that).