This post addresses a question that we are occasionally asked regarding billing and custom domains, where people would like to have separate billing for accounts within a single custom domain.

Here's an example scenario: I, Bron-the-person, have an awesome domain (let's say, and my friends all want to have accounts on the domain as well. I would rather they each paid FastMail directly, rather than me paying a giant bill and then having to chase them all up for their share. Maybe it's just my family, maybe it's a whole club of people; the underlying scenario is the same.

FastMail has billing infrastructure in place to bill users individually, so therefore it wouldn't be hard for us to support this model, right? Everybody would be happy - maybe a few users would close their accounts, maybe a few more would join. Maybe could even be available for any FastMail customers to sign up with, since it's such a cool name.

It seemed like a good idea once upon a time.

Unfortunately, FastMail wouldn't own, and if I, Bron-the-person, decided that I wanted to move my domain to a different provider, I could just point the nameservers or MX records elsewhere. All the other users with addresses or aliases in would lose the ability to receive email to that domain, and there's nothing FastMail could do about it.

Ownership of address space

At the core there are two different things being owned. One is the mailbox, say FastMail owns the server where the disk is stored, and creates all the database entries and server file locations for a mailbox with that address. The other is the domain, which is necessary to route emails to that mailbox. Unless they are both owned and controlled by the same entity, FastMail is placed in an impossible position, selling an account name in a namespace we don't control.

So we offer two choices:

  1. You can purchase accounts in one of the many domains that we control, and we don't care if you pay for them individually or as a group.

  2. You can bring your own domain, but then the owner of the domain must also be the owner of all the accounts within that domain. That way we aren't making promises that we can't keep and nobody's email ends up homeless.