I installed the actual version of raspbian

with apt install: motion fetchmail detox mplayer ripmime

Here is the link how to set the mail reception:

https://www.axllent.org/docs/view/gmail-pop3-with-fetchmail/

And the relevant part of motion config:

############################################################
# External Commands, Warnings and Logging:
# You can use conversion specifiers for the on_xxxx commands
# %Y = year, %m = month, %d = date,
# %H = hour, %M = minute, %S = second,
# %v = event, %q = frame number, %t = camera id number,
# %D = changed pixels, %N = noise level,
# %i and %J = width and height of motion area,
# %K and %L = X and Y coordinates of motion center
# %C = value defined by text_event
# %f = filename with full path
# %n = number indicating filetype
# Both %f and %n are only defined for on_picture_save,
# on_movie_start and on_movie_end
# Quotation marks round string are allowed.
############################################################

# Do not sound beeps when detecting motion (default: on)
# Note: Motion never beeps when running in daemon mode.
quiet on

# Command to be executed when an event starts. (default: none)
# An event starts at first motion detected after a period of no motion defined by event_gap
on_event_start /home/pi/play