eM Client fails to start.

Seems like eMClient does not shutdown properly, some process hangs, and prevents eMClient from starting again.

the process name is MailClient.exe. Only if I kill that process I am able to start eM Client.

Do you use any Anti-virus?

I am using Avast as antivirus.

In that case please disable SSL email protection in Avast settings and let me know if it helps. It started happening after their last update (Avast 8).

I went a step further and removed Avast from my machine and replaced it by MSE.
eMClient runs fine now.

Avast act as a ‘proxy’ for incoming.
Sometimes after uninstalling Avast you have to ‘reset’ your pop3 settings.