The required MX record ensures that all emails sent to the domain are forwarded accordingly. If this record is placed on a main domain, all emails, including your internal emails, will be forwarded to MAILINGWORK. Therefore, it is advisable to use a subdomain exclusively for MAILINGWORK mailings.
If subscribers reply to an email sent from the subdomain, the MAILINGWORK host receives these emails and forwards them to the corresponding mailbox on the main domain (e.g., mailbox@subdomain.maindomain.com is forwarded to mailbox@maindomain.com).
All bounces remain accessible in the MAILINGWORK account as usual.