This script read input from stdin and create/update an ICS file.
It's intended to run by postfix.
Works for now only for french messages but I'll be glad to merge languages ;)
Configure postfix to run the script when your addresses match (here calsync@)
# ensure that you have the correct permissions set up to allow Postfix to call external programs.
# Look for the default_privs parameter, which specifies as which user the external commands should be executed. This is important for security
default_privs = <someuser>
calsync: "|/usr/bin/python3 /opt/calsync.py"