Prior to delivering email to our customers, BlueTie performs a reverse lookup on the ‘From’ address of the sending mail server. This reverse IP lookup cannot be blank, it must resolve to a hostname. For example, BlueTie’s sending server response to a reverse IP lookup would be mail.bluetie.com.
- Reverse DNS lookup failures are temporary and will result in a temporary error bounceback while the server retries to send the messages sending servers will typically generate the first temporary error bounceback to the sender after 4 hours. Please note that this timeframe is configurable per server.
- The sending server will generate a permanent bounce after the retry timeframe has expired (this timeframe is also configurable, but is generally 5-7days), the sending server will generate a bounceback message stating that a permanent error has occurred and that the message was not delivered.
Resolution: If a sender should receive a bounceback stating that a temporary or permanent failure has occurred “450 4.7.1 Client host rejected: cannot find your reverse hostname” the administrator for that server should be contacted and a valid hostname should be given to the sending server.