SenderID filtering uses an additional record in public DNS to achieve this. SenderID filtering tries to determine if the sending SMTP server is actually allowed to send messages on behalf of the sender and his SMTP domain. One of the solutions to fight spam is to use SenderID filtering in Exchange Server 2010 and higher. There’s an Edge Synchronization configured between the Mailbox server and the Edge Transport server, and all inbound and outbound mail is handled by the Edge Transport server. The Edge Transport server is also behind a Kemp LM3600 load balancer, and it has a Digicert SSL Certificate with the same domain name. Besides the regular A and MX record, the IP address is also configured in Reverse DNS. In addition to this there’s an Exchange 2016 CU2 Edge Transport server with FQDN. The server is accessible via and (same IP address, behind a Kemp LM3600 load balancer) and configured with a Digicert UC certificate. There’s an Exchange 2016 CU2 Mailbox server hosting several Mailboxes. In the upcoming blogpost I’ll discuss SPF, DKIM and DMARC as implemented in my lab environment which looks like this: Just like SenderID and SPF, these solutions use public DNS for additional information as well, but since encryption is used most Exchange admin have some doubts about the complexity of DKIM and DMARC. Getting more popular for fighting spam are DKIM (DomainKeys Identified Mail) and DMARC (Domain-based Message Authentication, Reporting & Conformance). SPF looks like SenderID functionality, but it differs in the way how it checks email messages.īoth use public DNS records with TXT records where information is stored regarding the sending SMTP server, and this information is used by the receiving (Exchange) server to validate if the sending server is allowed to send email on behalf of the sender. Related to SenderID is SPF (Sender Policy Framework).

SenderID has been used in Exchange as a means for anti-spam for quite some time, as far as I can remember this was first used in Exchange 2010.

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