mails mark as spam why?

Hello everyone,

I have a few web sites and set them up with Virtualmin on the same server. When I try to send mail from some of my websites, receiver’s mail systems (such as hotmail, yahoo and some companies, universities) mark my mails as spam. I created all the records they requested for hotmail & yahoo but still same. I have the same record on my main web site and I don’t have any problem with it. The weird thing is the configuration is the same for all. I just wanted to learn if I created the correct dns records for the sites so I will post it here and waiting for some advices & helps. Thanks in advance.

PS: & ip address just for example

BIND DNS Master Zone:

$ttl 38400
@ IN SOA (
38400 )
@ IN NS IN A IN A IN A IN A IN MX 5 IN TXT “v=spf1 a mx ptr ip4: include:mail.domain1 ~all” IN PTR IN PTR