Auto Whitelisting

The SPAM score is used to provide a statistical average to monitor and properly place emails coming in frequently from specific addresses. This service has been put in place to help prevent false-positives.

Blocking IP Addresses

When a BlueTie interface user flags a message as Junk, by either using the Flag as feature or dragging the message to the Junk folder, the IP address of the sending server is recorded in BlueTie’s Complaint Table and may be blacklisted by BlueTie servers

In order to be blacklisted by BlueTie’s servers, the following criteria must be met:

1. There must be a disclosed number of complaints for one IP address.
2. All complaints must have been received during the previous 12 hours.

The blacklisting of an IP address will last for 12 hours for the first incident. Subsequent incidents will result in increased blacklisting time.

Each unique complaint drops off after 12 hours, however additional complaints during the block period will increase the time back to maximum of 12 hours until the complaints stop. For example, if a blacklisted IP address has 6 hours remaining on the BlueTie blacklist with only 1 complaint remaining in the complaints table and then an additional complaint is received; the IP address will be forced to restart a 12 hour blacklist period.  

Please note that the email sender will receive a bounceback message from the BlueTie servers.

DNS Reverse Lookup

Prior to delivering email to our customers, BlueTie performs a reverse lookup on the ‘From’ address of the sending mail server. This reverse IP lookup cannot be blank, it must resolve to a hostname. For example, BlueTie’s sending server response to a reverse IP lookup would be mail.bluetie.com.

- Reverse DNS lookup failures are temporary and will result in a temporary error bounceback while the server retries to send the  messages sending servers will typically generate the first temporary error bounceback to the sender after 4 hours. Please note that this timeframe is configurable per server.

- The sending server will generate a permanent bounce after the retry timeframe has expired (this timeframe is also configurable, but is generally 5-7days), the sending server will generate a bounceback message stating that a permanent error has occurred and that the message was not delivered.

Resolution: If a sender should receive a bounceback stating that a temporary or permanent failure has occurred “450 4.7.1 Client host rejected: cannot find your reverse hostname” the administrator for that server should be contacted and a valid hostname should be given to the sending server.

FQDN - Fully Qualified Domain Name

Send As Restrictions

Any user sending out of the BlueTie SMTP service, must use a valid email address/alias.  The following error will be received if the proper authentication is not used:

A valid address is defined as an address or alias that is found in the BlueTie system. Any address that is used to send mail from a mail client (such as Outlook) must also be found on the username that is using SMTP authentication. This can be verified in the user aliases section which is accessible via the Enterprise Manager.

Traffic Thresholds

To regulate traffic, throttling rules are applied to both inbound and outbound messages. 

Inbound Threshold

• BlueTie limits the number of incoming messages from one IP Address per hour
• Size restriction of a total of 160MB per IP address, per hour

Outbound Threshold 

• BlueTie limits the number of outgoing messages from one IP Address per hour
• If the number of messages sent per hour exceeds our limit, that IP address will not be able to send email for one hour.  Affected messages are not bounced. They are only temporarily deferred per the restrictions and delivered accordingly.