I just downloaded the latest version of eM Client and am unable to turn this spell check pop up off. I’ve been in settings, language, etc… and can’t stop this from popping up. I can barely type a few words before the window pops up and I’m forced to stop and “ignore all” until I can finish my e-mail. Extremely frustrating. Otherwise a great product.
I am having the same problem. I can’t even complete typing the first word and the spell checker window pops up. my version is 5.0.17595.0
Hello. Are you sure it is the Spell check window which pops up? Could you post here a screenshot please?
Yes. As soon as I start to type I get the following pop up:
It is strange. Have you typed any special character before the window was shown?
Hello- no. Seems like no matter what I do- the box is always there. I get two letters into a word and it pops up- I don’t even have a chance to spell a word wrong! 
Agreed. I opened a new mail, typed as fast as I could, and was able to get “I have u” in to the text feild and bam, the spell checker wiindow pops up and indicates Spell Check Completed. See below
I figured out what the problem was. I had a wireless keyboard that was malfuntioning with the F7 Key. The client is working buitifully thank you.