Gateway Filtering
Central TX Mail spam and virus filtering is a multi-step process that starts at our incoming email gateways, of which there are two. At these initial points of entry all messages are subjected to the following standard tests:
- Greylisting, a very common process that temporarily rejects unrecognized senders. More information...
- Reverse DNS, checks to make sure that the IP address used to send the email has a friendly name associated with it. Many spam messages don't have this record in place and thus fail this test.
- SPF (Sender Policy Framework), a method of verifying that the sender of an email message went through the appropriate email server when sending.
- Clam AntiVirus scanning and quarantine.
Messages that get flagged as spam or viruses are placed in a quarantine where they remain for 15 days before being deleted. These initial gateway tests catch about 90% of the spam and viruses that hit our system while catching false positives less than 0.01% of the time. False positives are legitimate messages that get flagged as spam. When a false positive is discovered in the gateway quarantine the email address or domain is placed on a permanent white list so that it won't get caught again.
Primary Mail Server Filtering
Once a message has successfully passed through a email gateway it enters the mail queue at the primary server. This is the server you login to at https://centraltxmail.com. The message remains in the queue for approximately 15 seconds where it goes through another round of spam filtering tests. Each test that is "failed" adds a score to the message. When all tests have finished the message will have a total spam score; this score determines how the message will be delivered to the end recipient.
The default spam scoring and actions for all Central TX Mail accounts:
- 0 to 7 points. Almost no probability of being spam. No action is taken and the message is delivered.
- 8 to 10 points. Low probability of being spam. [filtered] is added to the subject line and the message is delivered.
- 11 to 22 points. Medium probability of being spam. The message is delivered to the recipient's Junk Email folder on the server. Important: This does not put the message in the recipient's email client Junk Email folder! End users downloading messages to Outlook via the POP3 protocol will not see these messages. The only way to view them is to login to the mail server web portal at https://centraltxmail.com.
- Over 22 points. High probability of being spam. The message is re-routed to a system-level quarantine account where it will remain for 30 days and then be deleted.
NOTE: We are continuously adjusting these scores to fine tune the system. As a result, what may or may not have been considered spam one day might change the next day. The frequency of these adjustments should slow in time as we arrive at a baseline that provides the greatest effectiveness.
Control Filtering Weights and Actions
Domain administrators have total ability to override the spam filter weights and actions for all account users on the domain. In addition, domain administrators can delegate to account users the ability to override spam filter actions. NOTE: Individual account holders may only change their own spam filter actions; they cannot change spam filter weights.
At both the domain level (administrators) and individual account levels a Trusted Senders feature allows for the addition of trusted domains and trusted email addresses. Domains and addresses appearing in these lists will bypass spam filtering. In addition, email addresses in the contacts list are always considered trusted. NOTE: This applies only to the contacts list on the mail server, not the contacts list on an individual's computer mail client, such as Outlook.
False Positives
If an account holder believes a legitimate message did not get delivered the user should first login to the mail server portal at https://centraltxmail.com and check the Junk Email folder. If the sought for message appears in the folder, the user should right click on the message and choose Mark Not Spam. This action will do two things (1) place the message in the account Inbox, and (2) add the sender's email to the Trusted Senders list.
If the sought for message does not appear in the Junk Email folder and the account holder is very certain that the message was sent and not delivered, then the account holder should start a Support Ticket through this support portal. The following information MUST BE INCLUDED in the Support Ticket message:
- The email address of the recipient.
- The email address of the sender.
- The date and approximate time the message was sent.
- Brief explanation of what steps have been taken that leads to the suspicion that the message should have been delivered but hasn't.
Steps We Will Take
In the rare case that we discover a false positive held at the mail gateway level we will immediately release the message for delivery and white list the address at the gateway level. This will not stop the message from ending up in the recipient's Junk Email folder. It will be up to each individual to add email addresses to their own Trusted Senders list.
If the message cannot be found on the mail server or at the mail gateway we will search all log files for any sign that the message arrived at our system. If we can find no evidence that the message ever entered our system then we will consider the issue closed and recommend the recipient contact the sender and have the issue investigated on the sending email server.
Our Policy on Message Delivery
We go to great lengths to ensure that all our customers' outgoing messages are delivered and that our email server is not flagged or listed as a spam source. We do this by making sure that everything related to the email service is properly configured, secured and monitored. We don't think it's unreasonable to expect other email services to do the same thing.
We will do everything in our power to make sure legitimate incoming email gets delivered to its intended recipient, but we will not spend valuable time trying to solve problems caused by other email services. If a message that you expect to receive is flagged by our system as spam—or never even arrives at our system—because it came from an improperly configured sending source, it is not our responsibility to "fix" the problem. If an email fails to get delivered through no fault of ours and our customer insists we contact or work with another company to determine the reason for non-delivery, we will bill the customer at an hourly rate of $200 for our time spent on the issue, with the understanding that we have no control over the configurations of other companies' email systems and offer no guarantees that our efforts will solve the problem.