Anti-Spam

KyaHosting use many technics do fight against Spam. Here we wanna talk about those technics

 

Reverse DNS Control

Reverse DNS is a way of associating an IP address with its domain name. KyaHostying servers only accept messages coming from other servers with Reverse DNS well configured and working. But why is that? Reverse DNS is a setupthat only can be done by a ISP for their costumers. So the responsible for a server used to send Spam can be identified.

The reverse DNS identifier is contained in the PTR portion of the IP Zone File.

The IP Zone File contains all the different ways that your IP and domain name can be associated; each association serves a different need.

  • If the sender’s domain is the only domain sending mail from a specific IP address, we recommend that the reverse DNS entry (PTR Record) match the domain name (A Record), but we do not require it.
  • KyaHosting does require that all connecting Mail Transfer Agents have established reverse DNS, regardless of whether it matches the domain.
  • Reverse DNS must be in the form of a fully-qualified domain name – reverse DNSes containing in-addr.arpa are not acceptable, as these are merely placeholders for a valid PTR record. Reverse DNSes consisting only of IP addresses are also not acceptable, as they do not correctly establish the relationship between domain and IP address.

Greylist

In name, as well as operation, greylisting is related to whitelisting and blacklisting. What happen is that each time a given mailbox receives an email from an unknown contact (ip), that mail is rejected with a "try again later"-message (This happens at the SMTP layer and is transparent to the end user). This, in the short run, means that all mail gets delayed at least until the sender tries again – but this is where spam loses out! Most spam is not sent out using RFC compliant MTAs; the spamming software will not try again later.