Per T174893 let's create a step by step guide of how to request a MassMessage to be sent for WLM campaigns.

• Create documentation as a subpage of https://commons.wikimedia.org/wiki/Commons:Wiki_Loves_Monuments/Documentation
• Share it on wikilovesmonuments public list

Steps

• Get a list of all uploaders, which can be done with the 'Uploaders in cat' tool. There might be a better tool out there, too. Example: List of all uploaders for WLM-VE 2013
• On the Commons, make a list of all uploaders' talk pages; each listing should be formatted like # {{#target:User talk:USERNAME}} (see example)
• Draft the message you want to send on a new page. Do not include a header, as the MassMessage tool has a separate field for that. Ask an admin on the Commons to send the message out; I usually just post to the Admins' Noticeboard. See my example request on how to easily lay it out for admins. You basically want to provide the message, the header, and the list of user talk pages.