I created a mail server with debian 8 and iRedMail that works perfectly. The mail server runs 5 virtual domains and is configured with SPF, DKIM and DMARC
I receive correctly DMARC report for mails sent from the machine and everything is aligned.
I have a second machine that works as a Web Server, this machine sends daily reports to an @gmail.com account when I receive DMARC reports of this machine the SPF is aligned (because the IP is inserted in the DNS record) but the DKIM not presume because it is not configured.
How do I align the DKIM also the WEB machine? In addition to sometimes as the sending address is not the IP but the PTR (Reverse DNS) also in this case the DKIM is not aligned.
The following DNS configuration:
_dmarc.maildomain.com. 300 IN TXT "v=DMARC1\; p=quarantine\; rua=mailto:mail@maildomain.com"
maildomain.com. 300 IN TXT "v=spf1 a mx ip4:ip_mail_server ip4:ip_web_server ~all"
dkim._domainkey.maildomain.com. 300 IN TXT "v=DKIM1\; p=KEY"