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Hi,<br />
<br />
i receive a message of 5.1.2 - Bad destination host &quot;DNS Hard Error looking up mydomain.com' (MX): -- error message received by sender.<br />
<br />
This happen to one of the user want to send email you our mail server.<br />
<br />
we find no record of email received from the sender from our sid. meaning message has not reached my server and i have checked the spam blacklisted and found that there is a block from &nbsp;SORBS-SPAM.<br />
<br />
Due to that problem i have added sender email to the whitelists of my spam mail firewall and mail server.<br />
<br />
Above solution doesnt solve the problem the email send by sender still bounce.<br />
<br />
any idea?
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Hi,

i receive a message of 5.1.2 - Bad destination host "DNS Hard Error looking up mydomain.com' (MX): -- error message received by sender.

This happen to one of the user want to send email you our mail server.

we find no record of email received from the sender from our sid. meaning message has not reached my server and i have checked the spam blacklisted and found that there is a block from  SORBS-SPAM.

Due to that problem i have added sender email to the whitelists of my spam mail firewall and mail server.

Above solution doesnt solve the problem the email send by sender still bounce.

any idea?

mail server

A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

Switches / Hubs

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.