i mod r/boobsandbottles, a subreddit for parents who are combination-feeding infants (both breast- and formula-feeding) to ask questions and get support. awhile back i had to set the subreddit to "restricted" because it was being inundated with porn spam - it seemed people just saw "boobs" in the name and went apeshit. it's a very very small sub that is very slow-moving, so i would ordinarily not expect more than a handful of join requests over a 6-month span. in the last month or two, however, i have been getting multiple join requests every single day, almost all of them from brand-new accounts with zero history.

why are all these brand-new accounts requesting to join such a highly-specific subreddit? am i being recommended in some new user tutorial for some reason? is this a spam bot campaign that looks for any restricted subs to request access to? can i set an account age/karma limit on requests or add something to a filter somewhere so these accounts aren't being referred to my subreddit?