Variables de Python en una cadena multilínea

toname = "Peter"
toemail = "p@tr"
subject = "Hi"
content = f"""From: Fromname <fromemail>
    To: {toname} <{toemail}>
    MIME-Version: 1.0
    Content-type: text/html
    Subject: {subject}

    This is an e-mail message to be sent in HTML format

    <b>This is HTML message.</b>
    <h1>This is headline.</h1>
"""
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