Your sentence is o.k. However,if it bothers you, here is another way:
I have received an email from John's mother. ...Or
I have received the email from John's mother.
Yes, but the two possessives one right after the other sound a little odd.
You might say, "I have received the e-mail that John's mother sent to me," if you want to add a clause, or if you want to keep it short, say, "I have received the e-mail from John's mother."