There are a lot sent along with an email besides the To&#x2F;From names. The name is pretty easy to spoof, but the SMTP request and timestamps is much harder. Also most reputable senders now use SPF, a type of DNS record, to verify email servers. But email usually trusts by default, unless your servers are very locked down. You can still send &#x27;unverified&#x27; email, but its easier to trip spam filters if you send too much.