Since email address is a unique key for a CRM to work on contacts so it will not take up any such record which do not have email address. As in your case you are trying to edit the contact ( remove email address from the record ) and passing "" or NULL. HubSpot API will assume it as a new value for email property and will apply validation for the same. Since "" or NULL is an invalid format for email address field, hence returning 400 for the same.
In short, no way to remove an email from the contact unless or untill you attach a new email address with the same record.
is there a way to exclude email validation? I have user that mistype their emails something like aaa@gmail.comn, I would like to keep that way and not alter it when creating the contact on hubspot cc @himanshurauthan
Since email address is a unique key for a CRM to work on contacts so it will not take up any such record which do not have email address. As in your case you are trying to edit the contact ( remove email address from the record ) and passing "" or NULL. HubSpot API will assume it as a new value for email property and will apply validation for the same. Since "" or NULL is an invalid format for email address field, hence returning 400 for the same.
In short, no way to remove an email from the contact unless or untill you attach a new email address with the same record.