Problems emailing invoices & PO's via Outlook....again!

SUGGESTED

Up until yesterday all was good & I was able to email invoices & purchase orders. All of a sudden nothing happens. It looks like it's going through & then NOTHING. I have Outlook 2013 & it is open & it doesn't show anything in the outbox nor has anything been sent. It's like there's no communication between Sage & Outlook all of a sudden.

I know Outlook is working because I can go into my email account & email & I receive emails. 

Any ideas what happened & how to fix it?