It has got not to do with WP or BP
This is a problem with the host. Please write to them and/or set up a demo site and ask to test for themselves.
Thanks
I found with one site on one server – any emails sending via php had a weird return header thing from my server that did not get through some of this big three email clients no spam lists..
a plugin similar to https://wordpress.org/plugins/postman-smtp/
may change your wp to send via an smtp account on your server instead of php using a weird default server header.. you may need to create an smtp account for that work.. and even so there are other factors that could limit your email getting through.. (some shared servers are on backlist, some web hosting companies are given minus points, even if your web site is on the up and up)
There are a lot of things that could cause it to fail the ‘real mail’ test at some of these services..
