Just to add to that, in the website filtering settings, make sure “Allowed Websites” is positioned ABOVE “Blocked Websites” (Seen a few cases where Blocked websites have been above and hence had a higher priority which means the exclusions aren’t working)
Thanks for pointing that out Sanya. :-TU
Actuallt, I got that far by myself. Doesn’t work thou. 
Hi Muyfa666,
I am not sure why it still fails for you.
Once you have added it to the website filtering exclusions have you tried clearing your browsing data, or tried a different browser?
Thanks.
I tried it all, adding three entries; www.rarlab, rarlab.com and rarlab. I also moved allowed sites to the top.
No go.
Then I deleted all these settings, and tried to add just www.rarlab.com and now it works. Weird.
Since it work I won’t question it anymore thou… 
Let me explain why, when you enter a website to the exclusions rule, it doesn’t want a keyword, it’s a full URL it expects, so adding “www.rarlab” won’t work because the domain has “.com” after that meaning that it doesn’t match the full URL, similarly “rarlab.com” doesn’t have the “www.” part and “rarlab” has neither, but when you entered “www.rarlab.com” that is an exact match and hence will be allowed. The literally interpretation of the website entries is why we have wildcards like “" and “?” where "” matches any amount of symbols (which is why washij6 suggested “rarlab.”) and where “?” matches any one character.
Sorry, I missed the * in the post.
No matter. It does work now. Thank you all. 
I have the exactly the same problem which you have… and i 'm pretty nothing i can do about it …
Considering the amount of wasted time such a small thing is still causing since long time, and the extremely small effort it would take Comodo to resolve this issue, it’s very sad that not only Comodo still keeps www.rarlab.com blacklisted for no apparent reason (and yet has its moderators tell the users to whitelist it by themselves), it doesn’t even bother telling the users why was it blacklisted in the first place and why it’s still kept blacklisted. That sounds like we should expect Comodo to blacklist more harmless and highly respected websites for no reason. If I were a paying user I wouldn’t be too happy about this.