Thank you @all for all precious opinions and advices, but in my current situation, you missunderstood purpose of my post.
I don't have problem with spam on my blogs. Current configuration works just fine, and if it would fail, I have always Gmail's filters as second line of attack.
I've just noticed information about SPAM-preventing techniques that binds together Contact Form 7, CAPTCHA plugin and akismet. Enabled it on my company blog for a test purpose only and immediately noticed, that this team is just not working as it blocks correct e-mails from being sent.
I just wanted to warn others. You can easily spot false positives, which is spam not catched and delivered to you. But it is way harder to find out false negatives, where legit message is tagged as spam and thus not delivered.
I was lucky to catch such situation and so I was able to disengage this spam-preventing team. But there might be many people out there, that will want to run it on their company blogs, and will not be aware that this can possible block their customers from sending them letters.
That's just the whole story.
Thanks again for anything and sorry again for a bit offending words.