How to use these scripts:

1) generate a list of OSM usernames, that should be the target of a mail

2) retrieve the user id for each username (via the shell script)

3) edit the mail text in the python script

4) run the following command:
	( \
		cat html_header.inc; cat FILE_WITH_USERS_AND_IDS | while read line; \
		do username="$(echo "$line" | cut -f 1)"; \
			user_id="$(echo "$line" | cut -f 2)"; \
			./generate_send_message_url.py "$username" "$user_id"; \
			done; \
		cat html_footer.inc \
	) >mail_links.html

5) open the html file in your favourite browser

6) login to your openstreetmap account

7) click on each of the links in the local html file to send a single message