Processing External Messages Using a Secure Email Relay

A method, comprising:

• at a computing platform comprising at least one processor, a communication interface, and memory:
• receiving, by the at least one processor, via the communication interface, from a message source server associated with a first domain, a first email message and a first set of authentication credentials;
• validating, by the at least one processor, the first set of authentication credentials;
• based on validating the first set of authentication credentials, injecting, by the at least one processor, into the first email message, a DomainKeys Identified Mail (DKIM) signature of a second domain different from the first domain, wherein injecting the DKIM signature of the second domain into the first email message produces a first signed message that identifies itself as originating from the second domain;
• scanning, by the at least one processor, content of the first signed message, wherein scanning the content of the first signed message produces first scan results;
• validating, by the at least one processor, the first scan results;
• and
• based on validating the first scan results, sending, by the at least one processor, via the communication interface, to a message recipient server, the first signed message,
• wherein sending the first signed message to the message recipient server causes the message recipient server to validate the DKIM signature of the first signed message and determine, based on validating the DKIM signature of the first signed message, that the first signed message passes Domain-based Message Authentication, Reporting and Conformance (DMARC) with respect to the second domain.

One or more non-transitory computer-readable media storing instructions that, when executed by a computing platform comprising at least one processor, a communication interface, and memory, cause the computing platform to:

• receive, via the communication interface, from a message source server associated with a first domain, a first email message and a first set of authentication credentials;
• validate the first set of authentication credentials;
• based on validating the first set of authentication credentials, inject, into the first email message, a DomainKeys Identified Mail (DKIM) signature of a second domain different from the first domain, wherein injecting the DKIM signature of the second domain into the first email message produces a first signed message that identifies itself as originating from the second domain;
• scan content of the first signed message, wherein scanning the content of the first signed message produces first scan results;
• validate the first scan results;
• and
• based on validating the first scan results, send, via the communication interface, to a message recipient server, the first signed message, wherein sending the first signed message to the message recipient server causes the message recipient server to validate the DKIM signature of the first signed message and determine, based on validating the DKIM signature of the first signed message, that the first signed message passes Domain-based Message Authentication, Reporting and Conformance (DMARC) with respect to the second domain.