There are a number of message classes that can be processed by Exclaimer when applying Server-Side signatures to emails.

Please see the list below:

Exclaimer - Signatures for Microsoft 365

Supported Classes - Signature Applied
Message Class Details
IPM.Note E-mail messages
IPM.Task Tasks
IPM.TaskRequest Task requests
IPM.TaskRequest.Accept Responses to accept task requests
IPM.TaskRequest.Decline Responses to decline task requests
IPM.TaskRequest.Update Updates to requested tasks
IPM.Outlook.Recall Recalling sent messages from recipient Inboxes
Supported Classes - No Signature Applied

The following message classes are supported by Exclaimer - Signatures for Microsoft 365 but will not have a signature applied. By design, these types of emails cannot be modified after they’ve been sent and will bypass processing when received by Exclaimer’s servers:

Message Class Details
IPM.Note.Secure Encrypted emails to other people
IPM.Note.Secure.Sign Digitally signed emails to other people
IRM Protected Emails Emails protected using Information Rights Management
Unsupported Classes

The following message classes are not supported by Exclaimer - Signatures for Microsoft 365. By default, the Identify messages to send to Exclaimer Cloud transport rule will not pass these message classes to Exclaimer for processing:

Message Class Details
IPM.Appointment Appointments
IPM.Schedule.Meeting.Canceled Meeting cancellations
IPM.Schedule.Meeting.Request Meeting requests
IPM.Schedule.Meeting.Resp.Neg Responses to decline meeting requests
IPM.Schedule.Meeting.Resp.Pos Responses to accept meeting requests
IPM.Schedule.Meeting.Resp.Tent Responses to tentatively accept meeting requests

Exclaimer - Signatures for Google Workspace

Supported Classes
Message Type Signature is applied in transit
(Server-Side signature rules)
Signature is applied in Gmail
(Client-Side signature rules)
Calendar Y N
Send As Y N
Voting Request Y N
Voting Response N N
Read Receipts Y N
Recalling N/A N/A
Encryption N Y
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