Em Client sends emails fine and does not have any errors in the log but error message tells me failure to connect to server.

Em Client sends emails fine and does not have any errors in the log but error message tells me failure to connect and to check my settings, my setting never changed.  I tried turning off my firewall, no luck

You can try disabling your anti-virus application to see if that is the cause.

Otherwise, check to see that you have the correct settings. Go to Menu > Tools > Accounts and click on the IMAP tab for the problem account. You should have one of the following combinations:

Port 993 = Use SSL/TLS on special port (legacy)
Port 143 = Use SSL/TLS if available

Same problem. Em Client appear to send OK, but does not synchronise incoming with server.  Have red triangle with exclamation in account telling me I have no connection with the server.  I have not changed server settings!  Now I have tried all the options for SSL/TLS, but none work.  I have un-installed Em Client and re-installed.  I have removed my account and re-connected to my account all with no results.  There are no errors in the log.  Version number 7.2.38715.0,  Sometimes when messages do find their way into my inbox they are only a subject line with a message under it saying “Download message.  The message wasn’t downloaded because you’re not connected to the server”
The problem has now been going on for 2 days.

That could be a server problem, and not a connection problem. But try the settings above Henk. They are specific combinations, and if you have the wrong combination, it probably won’t work. Also, As I advised above, try disabling the anti-virus application just to see if that s the problem.

Tried all the different combinations. including the ones above.  Yes, it may be the server (Yahoo), but they say they haven’t changed anything.

Fixed now.  Removed the account from Em Client again and this time removed the database from my computer as well.  Re-booted and re-connected the account to Em Client, then allowed it to synchronise.  All has been OK for the past day.