The Signature 365 Agent for Outlook supports adding signatures to email so signatures appear directly below the email being composed, and to select an alternative signature if additional signatures have been assigned to them.
The Signature 365 Agent is available as an alternative if you want to deploy using MSI or ClickOnce instead of deploying the modern Signature 365 Outlook add-in via the Microsoft 365 Admin center.
Configuration page
https://app.signature365.com/integrations/outlook-agent
System requirements
.NET Framework 4.7.2 or later.
MSI package
Download link:
https://downloads.signature365.com/outlook/Signature365Agent-2.2.1.msi
ClickOnce installer
Installer link:
https://downloads.signature365.com/outlook/Signature365Agent.application
This version automatically updates when new versions are available.
Limitations of the agent
The Signature 365 Agent for Outlook does not support different signatures, campaigns or disclaimers based on internal or external email. The Signature 365 Agent for Outlook will select signatures, campaigns or disclaimers only based on new and reply/forward email.