Let's say you have a custom signature, and you put a link to your wall in it. Well, not every wiki has message walls, so you might want to make it so that your signature can make that determination. Add the following where you would put a link to your wall/talk page so your signature can know where to link to.
{{#ifexist:{{ns:1200}}|[[Message Wall:<your user name>|wall]]|[[User talk:<your user name>|talk]]}}
I would like to know how well it works. Lady Aleena (talk) 03:44, October 24, 2017 (UTC)