You can connect your Senders account to your Campaign Monitor account. For each sender, you will instantaneously know which of your mailing lists s/he is subscribed to.
Each time you receive an email from a sender, the Senders card will display the status of the sender with respect to your Campaign Monitor lists:
If the sender is not registered in any list, the Campaign Monitor banner will simply state "Not in any list."
To connect your Senders account to your Campaign Monitor account, go to your settings and switch the Campaign Monitor toggle on.
You will be requested to connect to your Campaign Monitor account:
...and allow Senders to access your account:
Once done, your settings will display the name of the account you are connected to.
Now each Sende.rs card you receive will display a Campaign Monitor row.