Client suddenly stops sending or receiving mail

Hi, I was running client 7.1.31849 working fine. Then with no changes made, mail just stopped working to my btconnect.com POP3 account. It has done this before but then suddenly starts working for no obvious reason - not this time.
I am online. I can ping the outlook.office365.com and smtp.office365.com IP addresses.
When I hit refresh, nothing happens and no entry goes in the Operations log or error.
I have upgraded client to 7.1.33101 with no effect. 
It seems like it needs a kick to start working but other than refresh what can I do?

Help!!

Many thanks
Rick

Addition to above after reading other comments I looked at sync bottom left. It says “Never synced”. Since this has been working fine I assume the never synced applies to the case since upgrading the client. What stops it synching considering nothing has changed since it was working? How can I force a sync - I know the mail server IPs are visible?

Thanks

Well if you have a BTConnect POP3 account, pinging a Microsoft server will prove nothing.

Can you temporarily disable your anti-virus application, then try again?

Hi Gary, Thanks for responding. those are the POP3 and smtp server names in the btconnect mail set up. On ports 995 and 587 respectively. My mail has been working fine with those settings fine, until just now.

I turned everything McAfee off and restarted the eM Client it made no difference. Is there anything else to switch off?

Can you make sure that POP3 port 995 has the security policy of Use SSL/TLS on special port (legacy) and SMTP port 587 is set to Force usage of SSL/TLS.

With those settings and the anti-virus disabled it should connect to the Microsoft server. If it doesn’t, maybe contact Office 365 support.