I think Dave is right,
I used to have similar problems only for sending if eg, I used Vodacom email but Neotel connection or cell c connection - I would then need to change the smtp from Vodamail to Neotel SMTP if using neotel internet or cell c SMTP if using cell c internet (Just call the internet provider and ask for the SMTP)
Hope you get it sorted out!
Did you like this article? Share it with your favourite social network.