sus4.net internet services
FAQ:Email Issues
Why is this sender's message returned to them?
Our spam abuse policies are more strict than other ISPs. The following error messages may help in determining why someone can not send you mail. Feel free to share this page with them so that they can solve their problem.
- Helo command rejected: need fully-qualified hostname;
This rejection notice means that the sending mail server is not identifying itself with a FQDN. This does not mean that it won’t deliver mail anywhere, but it won’t be accepted by mail servers such as ours that are configured to only accept valid communications from mail servers.
DNS Report provides a great tool for finding out what on the sending server are not configured correctly. Most likely with this error, the report will warn that the “Mail server host name in gretting” is claiming to be something other than what it is. Also see RFC2821 4.3.1 for more information.
- Client host [xxx.xxx.xxx.xxx] blocked using dul.dnsbl.sorbs.net; Dynamic IP Addresses
It is very poor net etiquette to send mail using a dynamic IP address. See our policy on spam for our stance on the issue. The senders’ ISP will provide them with an appropriate SMTP server to use to send mail. They should contact their network administrator about this issue and that it is causing their email to be rejected.
We determine the type of IP address from SORBS.
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