BuddyPress.org

Have you tried it default 2014 theme, bp running, and all other plugins turned off?

Does your server send emails from wp other ways successfully?
(like you go into wp backend add a user and tell wp to send an email with login credentials to yourself to test)

Have you tried contact form 7 or si-contact form plugins to see if your server allows wp to send emails?

Have you tested to see if it’s just users that use a gmail addy to try to sign up?
or is it all email services like yahoo, comcast, gmail, everything?

Could be a lot of things – but those are the things I would try to figure out first in order to fish out what could be done to make it better.

@zewitchi

with new servers, I try to use these two plugins:
Have you tried “contact form 7” or “si-contact form” plugins to see if your server allows wp to send emails?

on some servers they both work to send an email to my admin email account – on some servers only one of those will work (without tweaking smtp settings and such)

in my limited experience – if neither of those work – then I would write my server people and ask them if some kind of mod sec or php limiting setting that the server company sets would be preventing your wordpress install from sending email via php.

There are other ways to get WP to send emails – but your server people will usually see something in the error log, or know that they have your account limited in some way that either they will change for you, or tell you that you need a different hosting plan in order to use features like that – since they are sometimes abused by the hosting account leasee, or spam / hack programs that hit unsecured php scripts.

(I’m no expert, just had some experiences. I’m sure others know more about this than I do)

btw I tried to sign up an account with your site, and used one of my non-gmail non-yahoo addys, which usually lets everything through (no spm filters and such) and I never got an email – so I would check with your host first.