Hi @lukaszs45590312,
With respect to ACS, currently there is no substitution address you can give to test the delivery content, when you have level of personalization generated from custom resources. Workaround is you can have mock profiles and also you will have to differentiate mock vs real profile. Then populate sample data using the mock profile and try to segment the mock profile as one-off email delivery to test content before you send to target audience. Incase, if you're having different variant to the personalized data then you need to setup some process to setup additional mock profiles and populate the fields using data import.
Hope this helps.
Thanks!
Thanks, Sathees