Did it bounce back to you?
I've made an offer for you.
Yes, no problem.
You still have a record of the sending of the email?
In that case, you have given proper notice.
It is not your fault or your problem that the email address isn't working. It is theirs. If it is on their site then I don't know what else they expect you to do.
I would get a screenshot of their site though so they can't remove it.
Can I clarify anything for you?
All the best
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