Emailing in Accounts Hosted

Emailing in Accounts Hosted.
does anyone know when the ongoing issues will be fixed?
ie people getting their invoices when they are emailed from accounts hosted? we still have many customers who simply do not receive their invoices, nor are there any return to sender mechanisms in place to let us know who! I am talking in the 100's !
we have done all the tried techniques, ie adding as a safe sender etc etc. 
we are not going to email 1000 invoices to ourselves and then send out. we might as well go back to writing them out!
please reckon give us an answer on this!