Here's a context. A person has changed his main Facebook email address to
firstname.lastname@example.org. His previous email address
email@example.com. Assuming that the person will never change his Facebook email address anymore, I have this sentence:
The email address that was associated with his Facebook account is firstname.lastname@example.org.
I was thinking that
is email@example.com can be correct since the previous email address will never change (i.e., in the future, the previous email address would still be
firstname.lastname@example.org). On the other hand, using
was email@example.com sounds natural but I don't understand why it would be correct because I thought that
was is used to refer to a past event and
firstname.lastname@example.org is not an event.
I appreciate if someone could help me with my confusion. Thanks.