Performing API requests "on behalf of" Subaccounts
Primary accounts can make API calls on behalf of their subaccounts, e.g. sending messages, managing mailing lists, etc. This is accomplished by using the X-Mailgun-On-Behalf-Of header, which must contain the subaccount’s account ID.
Moreover, this header is a request header, not a message header. As such, this is not the h:header_value construct used for adding Reply-To fields, for instance. How to add request headers differs with each language; nonetheless, the below example shows how to add a request header in cURL.
Important Note: If the X-Mailgun-On-Behalf-Of header is NOT included, the action could occur on the primary account rather than the subaccount.
Request Header
X-Mailgun-On-Behalf-Of: SUBACCOUNT_ACCOUNT_IDWhere SUBACCOUNT_ACCOUNT_ID is a value like 646d00a1b32c35364a2ad34f. The header’s data type is a string, and each programming language likely will have the entire header (i.e. the header name and value) enclosed in single- or double-quotes (as shown in the below example).
Example cURL
curl -s --user 'api:PRIMARY_ACCOUNT_API_KEY' \
https://api.mailgun.net/v3/SUBACCOUNT_DOMAIN/messages \
-H "X-Mailgun-On-Behalf-Of: SUBACCOUNT_ACCOUNT_ID" \
-F from='Excited User <YOU@SUBACCOUNT_DOMAIN>' \
-F to='foo@example.com' \
-F subject='Hello' \
--form-string html='<html>HTML version of the body</html>'As you'll notice in the above example, the API key used is that of the primary account whereas the domain and account ID used is that of the subaccount.