I did a test for one of my user's mail settings on http://mxtoolbox.com/ and got the following warnings: Can anyone help me resolve these?
If you need dns on different subnets, you need an additional ip on a different subnet. SOA expire: RFC 1912 recommends 1209600 - 2419200 seconds (14-28 days). (https://mxtoolbox.com/problem/dns/dns-soa-expire-value) No SPF means, that you just have no SPF-record in your dns. Therer are several online-generators for spf-records. BTW: you should have a spf-record: http://blog.schaal-24.de/mail/der-sinn-von-einem-sender-policy-framework-spf-record/?lang=en
I added an SPF record. Now, the same test said I need a DMARC record. How do I set this up? Do I add it as a txt zone file, and use an online-generator like I did for the SPF record?
Install the dkim-patch from http://blog.schaal-24.de/ispconfig/dkim-patch-1-0/?lang=en, create a dkimkey and use the two new Wizards in a dns-zone (spf and dmarc).
