If the problem is email in the spam folder, another option might be to use the whitelist_to family of options for spamassassin.
This has the advantages of not affecting other domains hosted by the same MiaB installation as well as not being written over every time MiaB is updated.
Create a unique configuration file /var/spamassassin/uniquefilename.cf
Add one of the following to the file:
whitelist_to *@example.com
Some spammy appearing emails may still get declared spam, so if not strong enough use:
more_spam_to *@example.com
If still not strong enough, use:
all_spam_to *@example.com
Although these examples use * to catch all email addresses for the domain, you could also list the email addresses:
whitelist_to username1@example.com
whitelist_to username2@example.com
...
Be sure to restart stuffs after creating or editing the file:
$ sudo service spamassassin restart
$ sudo service spampd restart
$ sudo service postfix restart