Steps to set up email signatures on Exchange 2013:
Access your Exchange admin center. To do this open an internet browser and in the address bar type:
<CASServerName>is your Client Access Server computer name) and log in using domain Administrator credentials.
Go to mail flow, rules to arrive at the Exchange 2013 transport rules’ editor.
Click the + button to go straight to the transport rule creation wizard (and specify action type later) or the small downward arrow to first choose the action type (Apply disclaimers…).
By default the wizard starts up in simple mode, with only 2 configuration options: 1 condition (e.g. senders’ scope) and 1 action (Append the disclaimer…).Use the *Apply this rule if… section to define the conditions for your rule (complete list available here)
If the *Do the following… section is not defined yet, select Append the disclaimer… and click the Enter text… link. The disclaimer you design can contain text, Active Directory variables (in %%name_of_variable%% format; more in this article), HTML tags (including linked images) and CSS styles.
Click Select one… to select the action the rule will fall back to if the primary action fails. The options are: wrap (append the disclaimer to a new message with original message attached), reject (block message and send ndr to sender) and ignore (send message without disclaimer).
Click save and test your rule.
Or, to get more configuration options, click More options… . This will enable you to add multiple conditions, actions, exceptions, decide whether more rules should be processed, specify a time frame (recurring time frames not supported) and set audit configuration.
In the Choose a mode for this rule section select Enforce to deploy the rule, or one of the Test… options to have your rule’s actions logged to messages’ tracking logs, but not actually affecting the content of emails.
Afterwards you can enable/disable the rule (checkbox in ON column) and view its summary without accessing the wizard. To modify the rule configuration, highlight your rule and click the pen button (marked red).