GNU emacs RMAIL

Within emacs, there is also a sophisticated mail facility called rmail for more advanced users. This facility brings to bear the full power of emacs in handling both incoming and outgoing mail. To invoke RMAIL within emacs, run the command M-x rmail. The RMAIL utility will then extract all messages from the system mailbox and put them in the file  /RMAIL in your home directory and open a buffer RMAIL displaying the first unread message. The h key causes RMAIL to split windows and create a new buffer RMAIL-summary and list your messages. As you move up and down in the summary buffer the RMAIL buffer tracks the message on the current line. Here are a few other useful RMAIL commands:

h Refresh the summary buffer.
p Move to the previous message.
n Move to the next message.
<SPC> Space bar. Scroll down a page.
. Period. Jump to the top of the message.
r Reply to the message.
f Forward the message.
g Grab any new messages from the system mailbox.
s Save the modified RMAIL buffer.
w Write the body of the message to a file.
o Output the file to another RMAIL-format folder.
d Mark the message for deletion.
u Unmark the message.
x Do the deletions.
q Quit RMAIL.
RMAIL has useful pull-down menus. For example the Mail->Cite Original selection copies the original message into the body of a reply message at the cursor position.