To use the mutt mail user agent (available in the Classic Linux environment), first create a file  .muttrc  in your home directory, and into it insert a line that defines your preferred email address. For example,  .muttrc  might contain:

set from = "Some User <USER@rahul.net>"

In place of Some User enter your preferred full name, and in place of USER@rahul.net enter your preferred email address.

You may also optionally include the following two lines in your  .muttrc  file, but before you do so, please consult mutt documentation online to understand what they will do.

set use_envelope_from = yes
set edit_headers = yes

Then simply invoke mutt by typing  mutt  at the Linux shell.

Mutt has many different options, and you are advised to consult the many tutorials available on the Internet.

If you had a maildir format mailbox, e.g., ~/Maildir on the old servers, you can access it with mutt commands like the ones shown below.

To access an inbox in an old maildir format mailbox:

mutt -f ~/OLD/shell/Maildir

To access a folder called example in an old maildir format mailbox:

mutt -f ~/OLD/shell/Maildir/.example/

Mutt will also automatically recognize non-maildir mailboxes (in mbox format) with the same syntax.

Mutt can be configured by power users to access any number of mailboxes in various formats. Please consult documentation on the Internet.