Where are you creating the email_image_rels table?
Somehwere you need this code before you try to define the rel_type.
create table email_image_rels (
rel_id integer email_image_rels_rel_id_fk references acs_objects
)
You can't use the email_images table to hold the relationships the way it is defined.
It also appears you are trying to use email_image for a subtype of content_revision.
