You can use the IMAIL summary buffer to do almost anything you can do in the IMAIL buffer itself. In fact, once you have a summary buffer, there's no need to switch back to the IMAIL buffer.
You can select and display various messages in the IMAIL buffer, from the summary buffer, just by moving point in the summary buffer to different lines. It doesn't matter what Emacs command you use to move point; whichever line point is on at the end of the command, that message is selected in the IMAIL buffer.
Almost all IMAIL commands work in the summary buffer as well as in the IMAIL buffer. Thus, d in the summary buffer deletes the current message, u undeletes, and x expunges. o outputs the current message to a folder; C-o saves an attachment from the current message; r starts a reply to it. You can scroll the current message while remaining in the summary buffer using <SPC> and <DEL>.
The IMAIL commands to move between messages also work in the
summary buffer, but with a twist: they move through the set of messages
included in the summary. They also ensure the IMAIL buffer
appears on the screen (unlike cursor motion commands, which update the
contents of the IMAIL buffer but don't display it in a window
unless it already appears). You can always display the message indicated
by point using the <e> command (
When you are finished using the summary, type C-x k <RET> to delete the summary buffer's window.