Subdomain addressing
Subdomain addressing lets you make up addresses on the spot, under subdomains of your own domain, without creating aliases. It works the way Fastmail's does, and it is off until a domain's owners or admins turn it on. There are two kinds:
| Setting | Mail to | Reaches |
|---|---|---|
| anything@amy.domain | shop@amy.example.com | amy+shop@example.com |
| amy@anything.domain | amy@shop.example.com | amy@example.com |
With the first, the subdomain names the mailbox and whatever comes before the @ is its plus tag. So with plus-address folders on, shop@amy.example.com is filed in Amy's shop folder. With the second, the part before the @ names the mailbox (or alias, list or room) and the subdomain is ignored.
Some address forms let a sender strip the tag; subdomain addresses don't. amy+shop@ shows which part to remove, but shop@amy.example.com gives no such hint.
Turning it on
- On the domain's page, under Mail settings, choose Subdomain addressing and pick one of the two kinds.
- Add the wildcard MX record the domain's DNS records now list:
*.example.comwith the same mail server as the domain itself. If your domain's DNS is hosted here or set up automatically, the record is added for you. - Wait for DNS to update, then try it: send a message to
test@yourname.example.com.
From the command line: corpsuite domain set TEAM example.com subdomainMode=plus (or alias, or off).
What it does not do
- Only one level.
shop@amy.example.comworks, butshop@a.amy.example.comis refused. - Only for proved domains. A domain added without proving it is yours gets no subdomain mail.
- A subdomain that is its own domain here keeps its mail. If
sales.example.comis added as a domain (on this team or another), its mail goes to its own mailboxes. It does not go tosales+…@example.com. - Sending is unchanged. You cannot send as
amy@shop.example.comorshop@amy.example.com; you send as your own address. Replies to mail you received at a subdomain address come from your address. - Names with their own records. The wildcard MX does not cover a subdomain that already has records of its own (such as
wwwormail). Mail to those names goes wherever those records say. - Unknown mailboxes are refused, as on the domain itself. If Amy's account refuses tagged mail,
shop@amy.example.comis refused too.
Turning it off makes those addresses unknown again. Remove the wildcard MX record yourself if you no longer want it.