Blacklisted by CBL when using domain names in SMTP

[jorge ceballos]

Hi everybody,

After upgrading to Plesk 12, I switched on email sending limit to 50 emails per hour per account and also changed mail config to start using domain names in SMTP and less than 12 hours later became blacklisted by CBL - hotmail and live rely on this blacklist - ; the argument was we were sending bots and malware.
This server has been under ASL since over a year now and we are positive its clean; still we did a full scan and nothing came up and none of the mail accounts were even close to sending 50 emails per hour.
Being sure we were not sending spam nor malware contacted CBL and got whitelisted ..... for less than 24 hours.
This happened three days in a row until we switched back to the previous mail settings where domains are not used in SMTP greeting and since then, we haven't had any trouble with CBL.
Has anyone else noticed this behavior?
Any idea on how can we prevent being blacklisted while using domain names in SMTP greetings?

TIA

Regards,

 

[Mickael Salfati]

Hi everybody,

After upgrading to Plesk 12, I switched on email sending limit to 50 emails per hour per account and also changed mail config to start using domain names in SMTP and less than 12 hours later became blacklisted by CBL - hotmail and live rely on this blacklist - ; the argument was we were sending bots and malware.
This server has been under ASL since over a year now and we are positive its clean; still we did a full scan and nothing came up and none of the mail accounts were even close to sending 50 emails per hour.
Being sure we were not sending spam nor malware contacted CBL and got whitelisted ..... for less than 24 hours.
This happened three days in a row until we switched back to the previous mail settings where domains are not used in SMTP greeting and since then, we haven't had any trouble with CBL.
Has anyone else noticed this behavior?
Any idea on how can we prevent being blacklisted while using domain names in SMTP greetings?

TIA

Regards,

I confirm also this issue. All domains ips are CBL blacklisted with this settings.

 

[Ignacio Morandin]

Hi Jorge,

Nice to meet you.
I'm having the same problem here, but I didn't touch the email configuration. The server is clean and MailEnable queue is fine but CBL says I'm maybe part of a botnet.
I don't understand when you say "I changed mail config to start using domain names in SMTP". Can elaborate further?

Thanks in advance,

Ignacio

 

[jorge ceballos]

Hi Ignacio,

There are three ways to enable SMTP outgoing service:

1.- send from the domain's IP address
2.- send from the domain's IP address AND use the domain's name in the SMTP greeting
3.- Send from specified IPs

We had the reported problem with CBL when option #2 was used.
Switched back to #1 and we haven't had a problem since.

Option 2 is atractive to us as when a mail is sent, it should be obvious to have matching domains for the SMTP greeting and the arriving domain, instead of randomly have one of the hundreds of domains hosted in the server saying hello while the domain of the sent email is very different. I know this is not shown at first glance but many spam filters use this comparison as part of their spam evaluation.

Hope this was useful.

Regards,