Emails won't send and eM Client runs slow

I’ve been trialing eM Client for about 5 weeks now. Mostly it has run fine. I use the latest version (6.0XX) - the system says there are no new updates. I use eM Client to connect to my Exchange account at work. I have verified their server is working fine for everyone else at work. Lately eM Client has started to run slower and slower when sending and receiving emails. And just last night I can’t send any emails - though I am still receiving them. When I try to send, I just get the spinning wheel for about 5 minutes - then nothing - it doesn’t go to the sent or outbox tray - it just disappears, and the recipient says they never got it. Obviously this is critical in my decision to purchase…

Hello Jeff,
please try upgrading to the new version of eM Client 7 available on our website and see if it solves your issue.
If it continues we can set up Logs to monitor this issue.

Regards,
Olivia

I am using version 7.0.27943.0.  Takes over 30 seconds to load.  Has stopped (or become unreliable) about sending emails. Any suggestions?