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Error: "Fix reverse IP" ou "reverse dns lookup"
As an anti-spam measure, we reject messages coming from machines which have no reverse DNS entry (i.e. machines whose IP address does not match their name). If you have received a "Fix reverse IP" error message, this means that your ISP or person responsible for your DNS has forgotten to match a name to the IP address of your e-mail server. Get in touch with them to rectify this situation and you will then be able to send e-mails as usual (both through us and any other e-mail servers).
More information / References
See this FAQ (click here) along with RFCs http://www.ietf.org/rfc/rfc2821.txt:
Only resolvable, fully-qualified, domain names (FQDNs) are permitted when domain names are used in SMTP. In other words, names that can be resolved to MX RRs or A RRs (as discussed in section 5) are permitted, as are CNAME RRs whose targets can be resolved, in turn, to MX or A RRs. Local nicknames or unqualified names MUST NOT be used. There are two exceptions to the rule requiring FQDNs:
- The domain name given in the EHLO command MUST BE either a primary host name (a domain name that resolves to an A RR) or, if the host has no name, an address literal as described in section 184.108.40.206.
Link to this FAQ: