I am looking for a way to ultimately prevent a user, or anyone inside of an organization, from forwarding emails to outside of the organization, if the message was routed internally.
Given this scenario,
UserA@company.com sends an email to UserB@company.com, and no other recipients.
I want to prevent UserB from forwarding this email to bob@outside.com, because it should be for internal use only.
Keep in mind, if UserA@company.com sends an email to UserB@company.com AND bob@outside.com, UserB should be able to forward the email.
Basically, if the email was originally internal only, this should not be able to be forwarded, however, I do not want to prevent an email from being forwarded when there is already an on-going conversation between an internal and external user.
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I am having difficulty with the logic for this issue. So far, what I have tried was creating two rules, This does not seem to work.
Rule 1,
Apply rule to messages
from users Inside the organization
and sent to users Inside the organization
apply Classification
Rule 2,
Apply rule to messages
sent to users Outside the organization
and marked with Classification
and when the Subject field contains FW:
send Delivery not authorized, message refused to sender with5.7.1
Please advise the best way to go about this.