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Here's everything you need to explore Sendman, the SMTP relay for Microsoft 365, and bring it into your organization.
The problem
The server that only exists for the printers
Nobody reads mail on it. It stays online because a scanner, a nightly ERP export and an alarm panel only know how to open a port and authenticate.
One Exchange Server, just for printers
It doesn't host a mailbox anyone reads. It stays online because a scanner, an ERP export and an alarm panel only know how to open a port and authenticate.
Unauthenticated relays or shared passwords
An anonymous relay lets anything that can reach it send as anyone in your domain. A mailbox password stuck to 200 devices can't be rotated without a site visit.
Every Exchange advisory becomes your weekend
On-premises Exchange is one of the most attacked workloads there is, and Microsoft's Basic Authentication retirement is closing in on the workarounds too.
The fix
What Sendman gives you
Entra ID authentication
Usernames and passwords keep working as they are, validated against Microsoft Entra ID – no app registration, no consent, no directory to synchronise.
Anonymous relay, on purpose
Devices that truly cannot authenticate get a narrow lane that has to be switched on deliberately, scoped to an IP range, and still bound by sender and recipient rules.
Sender and recipient control
Regular expressions on both sides, enforced at MAIL FROM and at every RCPT TO. Nobody sends as the CEO, and nothing becomes an open relay by accident.
Searchable event log
Every authentication failure and policy violation, filterable by user, address, sender and recipient, with the rule that rejected it named in the entry.
Already modernizing? Go further.
Sendman is one piece of the puzzle. Here's the rest of it.
SCEPman
RADIUSaaS
RealmJoin
Autopilot Monitor
