There is often something wrong with o2.pl / wp.pl's IMAP servers.
Not the first time, and probably not the last time.
Not just in AquaMail, there are reports of issues in Thunderbird too.
Feel free to make a debug log and I'll tell you what's wrong, so you can contact o2 support.
"I checked other email client and there arent that kind of problems"
Sure, because AquaMail is the only mail app that actually connects to and works with mail servers.
All other mail apps work by telepathic transmission (so they don't consume battery either).