A complex question with a conflagration of ideas and concepts. 1. An MX record is a part of the domain name services and is used to direct email to the correct place when the mail is delivered. As such if you were having mail for mydomain.com delivered to a third party mail provider, then the MX record would point mail servers sending mail to your domain to that third party domain. 2. Thunderbird is a mail client, it get mail from a server based mail account and allows it's local management. It is not a mail server, not does it have anything at all to do with the MX record as it is only connecting to the designated server to download email for the mail accounts setup in it. 3. EMail on your registered domain with godaddy is send to the server mentioned in the MX record. As Thunderbird is not a server, there is no involvement at this point. 4. EMail hosting is big business, but there are lots of providers with lots of offerings, most costing less than the godaddy charges. have a look at this web page for just some options. https://www.techradar.com/au/news/best-email-hosting-providers There are offering there from around $1.99 a month. and each of those would be happy to provider the necessary MX details to redirect your domain email. My understanding is the service being offered by godaddy is contracted to them by Microsoft, and as such uses the proprietary exchange server. Perhaps the most expensive way to run a mail server, but also the most compatible with Microsoft outlook which is written from the ground up as a client for that server and which struggles with open mail protocols like IMAP and POP. It does however support all sorts of corporate features like calendar sharing. Personally I turned my Microsoft exchange server off some years ago. I am not a corporate and really it offered very little to my small operation, all I wanted was mail and a calendar.