I want to do the Frequency Capping to those Emails which are sent/triggered from the Marketing Cloud Connect.
I know that we can add the exclusion Script to the Journey Emails, Content Builder Emails, Automation Studio Emails and Triggered Emails to applied the Frequency Capping at the send time.
Similarly, is there any good way to add the Frequency Capping while sending emails from the Marketing Cloud Connect?
For sending SMS through an external service provider, one option is to get the external web service provider to create a custom Marketing Cloud Package to pass the contact data from Marketing Cloud to the web service. This will create an activity in Journey Builder that will pass the necessary contact details to the external web service for sending SMS.
Official Marketing Cloud Package documentation here.
Once you have the package details from the services provider (API key and endpoint URL etc), you can follow these steps for the custom activity to appear in Journey Builder:
Go to Settings > Administration.
Go to Account > Installed Packages.
Click New to add your custom package.
Define a name and description and click Save.
Click Add Component to add customer journey activity to the package.
Pick Journey Builder Activity.
The problem was that I didn't link my custom Data Extension with Contact on Contact Builder.
Solution:
I entered on Contact Builder, created a new Attribute Group. After that I clicked on "Link Data Extensions".
So I select my Data Extension (DE) and linked my Primary Key of my DE (Salesforce Contact ID) with Marketing Cloud Contact Key.
At the end I clicked on Save and executed my Journey with my DE as Entry Source. After about 1 hour I received tracking data records on Salesforce.
Best Answer
You can create an initial Auto Suppression data extension and then use the API to add a query that targets it. (You have to use the API to create the query since you can't select the Auto Suppression data extension as the target through the interface.)
The query (or queries) could include criteria based on aggregated sends counts by subscriber as @Lukas suggested.
Automating the query his works well for account-wide frequency suppression.