You can look at the full headers of the email and the originating Internet provider will be listed at the bottom.
However this is not full proof as this can be "spoofed" or forged.
You can send an email to the domain administrator complaining of this unwanted email. If you look at the sender's email address, where it shows the domain to the right of the @ sign, you can send an email to spam or admin or abuse @ the domain listed.
However the caveat is that the spammer may own their own domain in which case any email will be sent back to them anyway.
I usually recommend not to reply to their spam as it shows the spammer that your email address is active.
The best thing to do is to create a spam rule in your email programme so that any spam from this sender is automatically sent to a junk or spam folder.
How do you read your email please: do you use a programme or webmail?
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