Isn’t this a message from Kaspersky telling you that the domain has a bad certificate?
If it is, it really has nothing to do with eM Client except that a link from a message you received was trying to access that site, in which case you will need to decide for yourself if you want to continue or not.
I get this bad certificate message from kaspersky every time I start em client for about 2 weeks so I thought it is somehow coming from em client? Sorry for my lack of knowledge on this. If this message is generated from some past email I have received can you suggest a method to detect which email so I can remove it?
It could also be from an avatar search.
You get a similar warning when you use a web browser to access their website. I had a look. 
They are a subsidiary of Nordis, Inc. which seems very authentic.
Whatever the case, all it means is that the express… site has a bad certificate. I guess you can contact them and ask them to update their certificate.