selectbytes

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Feb 26, 2015
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hi there
when telneting from outside to the public IP address of a cPanel box, i can send email to any email address without being prompted to authenticate.

is this an open relay?

i thought that email should only be accepted inbound.
in addition, we have clients that complain about receiving a high number of backscatters which looks to a certain degree like a related issue.

any solution?
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
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when telneting from outside to the public IP address of a cPanel box, i can send email to any email address without being prompted to authenticate.
You should not have an open relay unless you have made custom changes to your Exim configuration to specifically enable it. Could you show us an example of the telnet commands you are using?

Thank you.
 

selectbytes

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Feb 26, 2015
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SMTP Restrictions was disabled (is that the default setting?). the open relay issue is solved now.
there is still an issue with backscatters.
one of our accounts is complaining of receiving hundreds per day.
i can indeed telnet
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,884
2,250
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I am happy to see the issue is now resolved, although it's likely there was never an open relay configured. Could you open a new thread explaining the backscatter issue in detail?

Thank you.