webmail box not working after adding cloudflare

hi, i am using contabo vps server with plesk panel. 5 domains are hosted. after adding cloudflare now mail is not arriving in my webmail inbox. also sent mails are going to spam box and even in some cases does not go through. may be some problem with mx record and cloudflare dns. if you know how to solve it then it will take only 5 monite to solve. so i will give $2 plus 5/5 positive feedback. if a five star positive feedback is important for you then this 5 minute $2 task is very worthy