Being able to effectively control spam through technology is a business necessity. DATAIR employs a multi-layered spam filtering system to reduce the amount of spam messages we receive. 

An unfortunate and unavoidable side effect of any spam filtering system are "false positives", the detection of valid email as spam.  While we have several safeguards in place to mitigate their occurrence, there are times when a false positive may cause email sent to us to not be received.

This is a summary of the types of filtering techniques we employ:

IP Address Blacklists

When you send us an email, if your mail server is listed as being a source of spam by any of the following third-party blacklist services, you will receive a non-delivery report (NDR) indicating that your message was not delivered and the specific blacklist where you are listed. We do not maintain these lists. If you receive a NDR, you will need to visit the site of the blacklist the non-delivery report indicates to be removed from the blacklist.

URL Filter Blacklists

If the message contains a URL (web link) listed at one of the following URI blacklists as being a spam or phishing site, your message will be blocked and you will receive a non-delivery report. These emails are not received by DATAIR. You will need to visit the site of the blacklist the non-delivery report indicates to be removed from the blacklist.

Sender Policy Framework (SPF)

We also attempt to verify that the email was sent from an authorized server for your domain. If that check fails, you will receive a non-delivery report.

Attachments

DATAIR strips attachments from messages from email addresses that are not in one of our databases as a known sender.

Message Content Spam Filter (MessageSniffer)

Messages that make it through the above filters are then scanned by MesageSniffer software where it is assigned a 'score' indicating the likelihood that it is spam.  If a high enough score is assigned, the email server will refuse the message and return a NDR to the sender indicating the message was determined to be spam.

Virus Scanning

We scan for viruses at two different stages of the message delivery process. If your message contains a virus, it may be deleted without being delivered or the recipient or sender being notified.

Conclusion

We apologize if you are inconvenienced by any of the steps we have taken to control the scourge of spam.  Without these protections, email would be entirely unusable as a means of communication for all clients, prospects, and business partners. If you, your IT staff, IT consultants, and ISP are unable to resolve emails being blocked/bounced by our server, please contact us via fax at (630) 325-2660 with a copy of the non-delivery report and we will attempt to help you resolve the issue. 

Thank you for your understanding.

Sample Error Messages

Below is a sampling the non-delivery report messages you might receive from us. They are designed to give the recipient the information needed to correct the problem.

For mail sent from certain countries which generate a high percentage of spam. The list of countries changes from time to time...

550 5.7.1 Rejecting due to security policy (email not accepted from your country)

For mail sent from a server which has been blacklisted by a third-party listing service as a source of spam...

550 5.7.1 Rejecting due to security policy - Your mail server (IP Address) is blacklisted @ bl.spamcop.net. See http://bl.spamcop.net for removal instructions. See http://www.datair.com/spam.htm for more info.

For email sent from a known bogus email address (No one should ever get this)…

550 5.7.1 Rejecting due to security policy - Bad Sender Address - Your email address (From Address) is blacklisted. See http://www.datair.com/spam.htm for more info.

For email sent to a mailbox that doesn't exist...

550 Mailbox unknown - Contact [email protected] for further information

For email sent to an ex-employee…

550 Mailbox unknown - No longer a valid email address. Please resend to [email protected]

For email that contains URLs (web addresses/links) that are blacklisted by a third-party listing service...

554 Transaction failed - content blacklisted at black.uribl.com. See http://www.datair.com/spam.htm for more info.

For email that was detected as spam by the Spam Assassin spam filtering software. If your email address is in our database, you will not receive this…

554 Transaction failed - Your email was detected as spam by Spam Assassin. See http://www.datair.com/spam.htm for more info.

 

Revised 12/29/2017