What is the name of the Dovecot configuration variable that specifies the location of user...

 The Dovecot configuration variable that specifies the location of user mail is mail_location. This variable defines the format and path of the mailboxes, and it can be overridden by userdb or namespace settings. The format of the mail_location specification is:

:[:=[:=...]]

where  is one of the supported mailbox formats, such as mbox, maildir, or dbox;  is the absolute path to the mail directory; and = are optional parameters that modify the behavior of the mailbox format.

For example, a mail_location setting for maildir format could look like this:

mail_location = maildir:~/Maildir

This means that the user’s mail is stored in the Maildir subdirectory of their home directory.

References: You can find more information about the mail_location variable and its parameters in the following resources:

Mail Location Settings — Dovecot documentation

Config Variables — Dovecot documentation