I've created an account at heliohost with my domain (melda.info). After setting up e-mail accounts it turned out that a few SMTP servers rejects the mail. Sample error message:   
host x.mx.invitel.net [62.77.203.21]: 554 5.7.1 Client host rejected: 
    cannot find your hostname, [65.19.143.2]   
After searching for help, it seems to me that according to most of the websites I need reverse DNS, but it's missing ( http://www.intodns.com/heliohost.org ). Would it be possible to set reverse DNS? If not what can I do with these SMTP servers?   
Thanks, 
asalamon