Filter custom data object records based on nondedupe field

Hi Team,

We are trying to fetch all records from a custom data object which has a particular email , email field  is not a dedupe field and while trying to get the records via restapi we are getting invlalid filterttype "emailaddress" error since its not a dedupe or a searchable field.

Any pointers towards reading the infomration from custom object based on non dedupe field and can we also get help from marketo team to support searching based on this non dedupe field.