I have discovered that our site is not sending any emails. Usually when a new User is added they receive an email with their login details and we receive a 'New User Registration' confirmation email. Neither of these emails were received for the latest batch of users I uploaded. (I tested again adding a single new user and same problem.) Also, under their Group I checked the 'Welcome Email' to send an email when a new member join the group. No email was sent when I added the new users to their group. So I used the option 'Send an email notice to everyone in the group' but again nothing was sent.
We have WordPress 3.9.3 , SB Welcome Email Editor 3.9, Membership Premium 126.96.36.199, BuddyPress 2.2.1, BuddyPress Activity Plus 1.6.1, BuddyPress Group Email Subscription 3.5.1 and BP Group Email 1.0.6.
Many thanks for your help