Knowledge Base

Signatures are not added


Signatures are not added by a program from the CodeTwo Exchange Rules family.


There might be several reasons for such behavior. The most probable causes and adequate solutions are described below.

Missing component in a multi-server Exchange configuration

If you work in an environment with more than one Exchange server, make sure that the Exchange Rules Pro Service component is installed on all the servers with the following roles:

  • Exchange Server 2010 and 2007 - on all Hub Transport role servers,
  • Exchange Server 2019, 2016 and 2013 - on all Mailbox role servers.

Detailed installation instructions are available in the user's manual of your CodeTwo software:
CodeTwo Exchange Rules Pro | CodeTwo Exchange Rules.

Emails processed by servers without the Exchange Rules Pro Service will not be stamped with signatures.


To list all your machines with Microsoft Exchange Server and their roles, follow the instructions from this Knowledge Base article.

Insufficient licensing in a multi-server environment

If many Exchange Servers are handling your mail flow, you need to enter a CodeTwo Exchange Rules license key on each server with the Mailbox (in the case of Exchange Server 2019, 2016 and 2013) or Hub Transport (Exchange Server 2010 and 2007) role in your environment. Otherwise, CodeTwo Exchange Rules will process only those emails that pass through the licensed servers.

You will receive a separate license key for every server. Detailed instructions on how to activate the program are available in the user's manual of your software version:
CodeTwo Exchange Rules Pro | CodeTwo Exchange Rules.


You can check which servers are licensed by clicking the Server Monitor button on the program’s toolbar (Fig. 1.).

Checking if all Exchange servers are licensed.
Fig. 1. Checking if all Exchange servers are licensed.

Unsaved program changes

Each time you finish configuring rules in our program, you have to save the changes or the rules will not be applied. This is not done automatically to prevent you from unwanted modifications. You have to click the Submit changes button every time you want to apply the settings to all of your servers.

Missing signatures in RTF and Plain Text format

By default, the editor opens with an HTML tab that allows you to design a signature for most of email clients. However, some messages are sent in the RTF (e.g. meeting requests) or Plain Text (especially from mobile devices) format. Ensure that you have configured all formats of your signatures. All CodeTwo Exchange Rules family products (standard and Pro) have the Convert button available in the editor for easy conversion between formats.

CodeTwo Exchange Rules Transport Agent is not installed

The CodeTwo Exchange Rules Transport Agent is a part of the Exchange Rules Pro Service set of services and is responsible for processing all your messages. It may happen that although you selected the Exchange Rules Pro Service component when installing the program, the Transport Agent has not been installed together with other services. 

To check if the CodeTwo Exchange Rules Transport Agent has been installed on your machine, open  Exchange Management Shell and execute the following command:


Look for the CodeTwo Exchange Rules entry. If it is not displayed, install the agent manually.

Long list of rules

You have plenty of rules defined and you are not sure if a user whose messages are not stamped with signatures is defined in any of the rules' conditions or you would like to confirm that this user is not excluded in the Exceptions tab. The easiest way to verify it is to create a new, separate rule only for that user and move it to the top of the list of rules. It will allow the program to process the newly created rule as the first one, so that you can be sure that the rule is executed for this particular user.

This is not a solution itself, but a diagnostic step that allows you to verify if emails sent by this user are processed by the software at all. If it turns out that the rule adds signatures correctly for the user, you need to carefully check all of the other rules' conditions, exceptions and options, to find where the signature processing might be interrupted. If the signature is still not applied, consider checking the other reasons mentioned in this article.

The license limit is exceeded

The licensing mechanism assigns a license to each SMTP email address for which a rule is applied at least once by the software. Once the number of the licenses you purchased has been exceeded, any new SMTP email addresses will not be processed by the software (signatures will not be added to the corresponding messages). What is more, even if a user with a corresponding SMTP email address is no longer active in your AD, this person might still be assigned a license. Resetting the licensing counter is the easiest way to restart counting the license consumption, omitting the inactive users.

Complexity of rule conditions

Another reason to why signatures are not added may be related to complex conditions defined for a particular rule. If you are adding several conditions, the logical operators between them are extremely important and have to be properly selected. By default, each consecutive condition is added with the AND operator. Always make sure that this is the right operator, as sometimes you may need the OR logical relationship between certain conditions. In the graphical view it may not always be that obvious of what to expect, so please always double-check the result with the mathematical notation appearing automatically at the bottom of the window, in the status area (Fig. 2.).

KB545 - 1. Complex conditions
Fig. 2. Conditions' matrix.

Rule options stop the execution of other rules

Double check if some of the rules' options do not stop the email processing flow unexpectedly (Fig. 3.). Improper settings of this section may prevent consecutive rules from being executed. You may decide whether subsequent rules should be processed or not depending on the processing result of a rule positioned higher on the list of rules. It might sometimes happen that one of the defined rules is accidentally set to stop the program from processing any subsequent rules regardless of the rule's processing result (i.e. regardless if the rule is applied or not, the subsequent rules will not be executed at all).

KB551_2. options
Fig. 3. Rule options.

Changes made to AD objects defined in the program are not refreshed

If, for example, you add a user to an AD group and this group is defined inside a rule's condition, it may not be detected instantly by CodeTwo software. The reason is simple - by default, any changes to AD are refreshed every hour. You may, however, manually enforce immediate refresh or adjust this mechanism to suit your needs, following the guidelines described in this article.

Other reasons. Log file diagnostics

Carefully check all the conditions, exceptions and options of a rule that is not applied and send a test message that overlaps with the rule's criteria. Give it a unique subject, like “test_message01” to be able to trace it inside the program logs. If the signature is not appended, you can open the program logs and easily search for the test message by providing the message subject. Once you find it, you may verify the conditions' statuses inside the log file; these statuses explain why and at which point the signature processing was stopped.

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