When Rmail displays a message that does not fit on the screen, you must scroll through it to read the rest. You could do this with the usual scrolling commands:
M-< (see Scrolling), but in Rmail scrolling is so frequent that it deserves to be easier.
Scroll forward (
Scroll backward (
Scroll to start of message (
Scroll to end of message (
Since the most common thing to do while reading a message is to scroll through it by screenfuls, Rmail makes
S-SPC) do the same as
rmail-beginning-of-message) scrolls back to the beginning of the selected message. This is not quite the same as
M-<: for one thing, it does not set the mark; for another, it resets the buffer boundaries of the current message if you have changed them (e.g., by editing, see Rmail Editing). Similarly, the command
rmail-end-of-message) scrolls forward to the end of the selected message.