SOLVED Easy FIX your SMTP banner, SMTP greeting and Reverse DNS for Dedicated IPs

fcbinfo

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Moderator Note:

If you're reaching this thread due to the SMTP failure report on MXToolBox, keep in mind these are false positives and should not effect email delivery to/from your system. The following resource explains why this happens and provides a workaround if you want to ensure the test passes:

Tutorial - MXToolbox SMTP Failures (false positives)


Thank you.
 
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cvcvishnu

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Feb 8, 2015
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Hello,

I am facing the same issue. I have a domain and while checking in the MXToolbox site it shows "Reverse DNS does not match SMTP Banner". Please help me to fix the issue.

Awaiting a quick response from any one
 

Sam Nawi

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Feb 27, 2016
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Well,

after hours of finding solution of my problem as attached below.
This is the problem I got before.. Long time delayed and smtp banner.
before.jpg

then after looking for the setting on WHM - EXIM Configuration Manager.

there are 2 main setting, I think the last one is the new..
Dedicated.jpg

here the key
introduce.jpg

then voila..... my server was perfectly set up
after.jpg

Sorry for bumping this old thread.
Just for my archive information..

Regards, all..
 
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cPanelMichael

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Hello :)

Keep in mind that while disabling the "Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam" may allow you to pass those online tests, it will allow more SPAM to come into your server. Enabling it should not negatively affect interactions with actual mail servers.

Thank you.
 
Apr 12, 2016
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Well,

after hours of finding solution of my problem as attached below.
This is the problem I got before.. Long time delayed and smtp banner.
View attachment 35241

then after looking for the setting on WHM - EXIM Configuration Manager.

there are 2 main setting, I think the last one is the new..
View attachment 35231

here the key
View attachment 35221

then voila..... my server was perfectly set up
View attachment 35251

Sorry for bumping this old thread.
Just for my archive information..

Regards, all..

Dear Sam,

Thank you so MUCH, you really got me in the right directions and I was able to make the e-mails be sent/received correctly for the company the I work. And thanks to cPanelMichael too for warning about delay in the server and that would not affect e-mails! It does affects tests websites but not e-mails.

Best whises,
Pedro Henrique

Ps.: Sorry for my bad english, some words I can't remember.
 
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cPanelMichael

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New UHHH, I turned off the delay as you discribed above and now all is fine; but why does the babber-message disappear?
It's a limitation of the third-party utility you are using (MXToolBox). The option results in a timeout in their test, leading to a false positive. I recommend leaving the option enabled now that you've confirmed it's the reason for the false positive.

Thanks!
 

cPanelMichael

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Apr 11, 2011
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Quick question... This file does not exist in cPanel Exim. Anyone have a solution?
Hello @rogerw,

That's by design. We stopped creating and utilizing the /etc/mail_reverse_dns file starting with cPanel & WHM version 11.50. Any references to it that you see presently stem from user-submitted workarounds. Can you let us know the specific problem you are facing so we can guide you towards the best solution?

Thanks!
 

aUserName

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Sep 15, 2016
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...
SMTP Banner Check Reverse DNS does not match SMTP Banner
...
any idea how to fix it?
For anyone still wondering, since it isn't addressed in the Moderators note linked in the first post.
This is relatively easy to fix. However, there is no way to do it without root access. Goes without saying that cPanel likely wont recommend or support it.

You need to modify the Exim Configuration file and change the smtp_banner line(s) to make use of a lookup. We also need to manually create a file to act as our lookup database.

First, create the lookup file at /etc/exim_banner_addresses and place each mapping on its own line using the following format:
Code:
192.168.1.234: myhost.domain.tld
10.1.2.3: host2.domain.tld
Now edit the exim config, found at: /etc/exim.conf
Search for the following lines:
Code:
smtp_banner = "${primary_hostname} ESMTP Exim ${version_number} \
\#${compile_number} ${tod_full} \n\
We do not authorize the use of this system to transport unsolicited, \n\
and/or bulk e-mail."
Replace the above lines with these:
Code:
smtp_banner = "${smtp_active_hostname}"
smtp_active_hostname = ${lookup{$interface_address}lsearch{/etc/exim_banner_addresses}{$value}{$primary_hostname}}
Save the changes, and restart Exim to see the results.
You may also want to set the config file to read-only.
Again, this is not an automatic solution. In addition to manually adding new mapping entries - you will likely need to verify updates to Exim don't also require config updates, or need to manually re-apply this patch from time to time.

One could think cPanel would already support this along side their other dedicated IP functionality. cPanel is full of stuff like this though. I'd make a feature request but I don't feel like writing a short story to explain it, or waiting months or years for it to gain traction with the devs. I'll leave that to someone who's good at it.
 
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KaiserTom

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Jan 17, 2018
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For anyone still wondering, since it isn't addressed in the Moderators note linked in the first post.
This is relatively easy to fix. However, there is no way to do it without root access. Goes without saying that cPanel likely wont recommend or support it.

You need to modify the Exim Configuration file and change the smtp_banner line(s) to make use of a lookup. We also need to manually create a file to act as our lookup database.

First, create the lookup file at /etc/exim_banner_addresses and place each mapping on its own line using the following format:
Code:
192.168.1.234: myhost.domain.tld
10.1.2.3: host2.domain.tld
Now edit the exim config, found at: /etc/exim.conf
Search for the following lines:
Code:
smtp_banner = "${primary_hostname} ESMTP Exim ${version_number} \
\#${compile_number} ${tod_full} \n\
We do not authorize the use of this system to transport unsolicited, \n\
and/or bulk e-mail."
Replace the above lines with these:
Code:
smtp_banner = "${smtp_active_hostname}"
smtp_active_hostname = ${lookup{$interface_address}lsearch{/etc/exim_banner_addresses}{$value}{$primary_hostname}}
Save the changes, and restart Exim to see the results.
You may also want to set the config file to read-only.
Again, this is not an automatic solution. In addition to manually adding new mapping entries - you will likely need to verify updates to Exim don't also require config updates, or need to manually re-apply this patch from time to time.

One could think cPanel would already support this along side their other dedicated IP functionality. cPanel is full of stuff like this though. I'd make a feature request but I don't feel like writing a short story to explain it, or waiting months or years for it to gain traction with the devs. I'll leave that to someone who's good at it.
Thank you for the post.

This should be implemented as standard! 100%
 
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