This template is not blank, it adds a little icon in the top-right corner. See?

This template adds your username to Category:Wikipedia MassMessage senders.

Place {{Massmessage-sender topicon}} anywhere on your user page.

This icon is based on {{Top icon}}.

{{Massmessage-sender topicon
| icon_nr             = the icon number determines the offset of the topicon
| extra_offset        = an additional offset that you can use to force or adapt (in case you have non-20px wide elements in your topicon row)
| nocat = yes         = disables the automatically added category (default = no)
}}