Annoying frequent security messsages from Mozilla Thunderbid

[Broadback]

"Add Security Exception" You are about to override how Thunderbird identifies this site. There are several options to take, however non of them seem effective. It virtually happens each time I open a particular mail box. I'd love to get rid of it, any suggestions please?

[Broadback]

After a lot of trouble I find that is is how Eset delas with Startles emails. So I have decided to send the information and password in clear. That has stopped the problem, but does it make my emails insecure?

[Simon]

Can you not set an exception in Eset, rather than 'de-securing' your email login?  That is, if that's what you've done.  I'm not quite sure I follow the bit about "Startles". 

[Broadback]

Setting up exceptions in Eset? Ha yet another learning curve to battle up!