Tagging your Netcore Email API emails lets you easily search activity, compare stats, and more. Some examples of Tags are: Invoice Emails, Forgot Password/OTP, Newsletters, etc. Add tags to emails while sending emails through API or SMTP.

Here are a couple of examples of how to pass values to X-apiheaders in your emails:

X-TAGS: Forgot Password;

You can have multiple comma separated tags assigned to the same email.

Here is one example:

X-TAGS: Forgot Password, Transactional Email;

Once the Tags are assigned to emails, you can analyze the same under your Netcore Email API account.
The X-TAGS that you add will be stripped from the final email because they are headers for internal tracking purposes. So you can expect to not actually see these headers in the final email.

How to use it in API please refer to the below link.