eM client has been unable to connect the update server for at least 14 days.

eM client has been unable to connect the update server for at least 14 days. 
To be able to continue using this product, please ensure that the server is 
accessible from your network.

Last attempt resulted in the following error:
The underlying connection was closed An unexpected error occurred on a send.

the application will now run in offline mode

Are you using Windows XP?

If you are, please see https://forum.emclient.com/emclient/topics/windows-xp-no-longer-supported-issues-with-connecting-to-…

I have the same issue.  Well, more specifically my elderly parents who always get me to help them.  Windows 10.  About 2 weeks ago I switched virus protection, now just using the Windows 10 built in defender.  I suspect that has something to do with it, but how do I change it?

I never experienced the same issues with Defender as you get with third-party  anti-virus applications. But if it is Defender you could disable it and see if there is any difference. Would be good to know if that works.

More likely is a VPN or Proxy that is responsible.

Don’t use a VPN.  Actually I did disable defender and no help.  So I guess that is not the problem.  So where/what/how do I look for/change the proxy?

I don’t know Bevin. Depends on what proxy you are using.

Same here (running Win7Pro). Started appearing in the last few days. Last time it happened was Jan 2017. I didn’t change anything (firewall, anti-virus). It stopped appearing after a week or two.

You can always update manually by going to http://www.emclient.com/release-history