I want to be able to send email to any subdomain I like and not have to configure A records and MX records for each subdomain. Ideally I could send an email to firstname.lastname@example.org and email@example.com and not have to configure anything other than my original domain.com.
My current setup:
I have a domain (domain.com) and want to have multiple subdomains. (a.domain.com, b.domain.com, c.domain.com, etc).
I have an MX record setup to point to domain.com and all email works fine for that domain. I have NOT setup A records for all the subdomains (and really don't want to).