Multiserver Multidomain mx, DMARC etc

I have setup my mutliserver installation and I create a couple of email domains. Since postfix doesn't allow multiple SSL for each mail.domain.com I am using a main mail.domain.com for sending emails with SSL cert by Lets Encrypt.

My questions now are:

a. The dns records that are created by default for each domain mx mail.domain.com for each virtual domain should be replaced with the main mail.domain.com? And if yes then all virtual domains should have DMARC records in the DNS section for the main mail?
b. If not should I leave the default mx records for each domain intact and create DMARC and SPF records for each one?
c. Or there is nothing to be done and just use the main mail.domain.com in each client for sending and receiving from each virtual domain?

Finally is there a way to guide all rejected, quarantine etc mails (incoming and outgoing) to a specific mailbox so I can track down all issues and adjust my spam policy for postfix? (since a lot of mail servers don't strictly comply with all the standard rules for emailing)

Thanks in advance

 

Thats great.
In the server config of the mail server, under the mail tab, the form should writes in main.cf of postfix right?
I have done all main.cf configuration manually and i added a bunch of rbls and my relayhost but the form doesn’t show it. If I fill out the form so I can make changes throught the panel instead of editing manually will this rewrite and create duplications?

 

Where do these parameters write at? Does this work for spam that is rejected on the mta or only if spamassasin or amavis (for viruses) kicks in and marks the incoming as spam?

 

I entered my email in all the * lover text fields, but don't get any emails. Does this also apply on mta blocking besides amavis?