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Sendmail SMTP server issue

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7 replies

by rajaroychoudhury

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Hi,

I have configured sendmail SMTP server in Redhat Linux machine.
The linux box is using the ISPs DNS server to resolve the domain name.
We have a mail server hosted by third party. In our organisation we would leke to use the Sendmail SMTP Server to relay mails to outside world. As our ISP will not be providing their SMTP server to relay our mails. Hence we thought of creating a SMTP relay server using Sendmail in Redhat linux 7.
Now whenever I try to send mail through this machine it gives me this error "User Unknown"
Please if I need to attach the maillog file?

Please let me know what I should do to resolve this issue.

Regards,
Raja

7 replies

by mike o

If you're getting "user unknown", there could be two problems that I can think of offhand.

First, make sure you're creating accounts for all of your users on the Linux box. I realize this sounds obvious, but you're not saying when or where you receive this message, so I feel I best bring it up. Anyone using the Linux server as their SMTP server should have the server's address and their user name and password ON THAT SERVER keyed into their email client.

The only other explanation I can think of at this point is your users are simply typing in "johndoe" as the address rather than a full email address (such as "johndoe@somedomain.com"). If this is happening, the server will attempt delivery to user johndoe on the Linux server and if it doesn't exist will kick back an email with the user unknown error message.

by darry

Raja,
Even without using a seperate relay server within your organization, I suggest you just needs to provide the DNS Server IP address in the TCP/IP properties of the Linux box. Or, you can try DNS forwarders within your organi'n. Now try to senda outside mail & let me know the results.

Cheers!!!

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