Hey {{contact.first-name}},
I hope you're doing well.
I'm reaching out from [newsletter name], a [brief description of your newsletter]. We're currently looking for partners who are interested in sponsoring and advertising in our newsletter.
Given your expertise in [relevant industry or field], I believe your company could benefit from reaching our engaged audience. We have a [brief description of your audience] and offer various sponsorship packages tailored to meet different marketing objectives.
Would you be interested in exploring this opportunity further?
Looking forward to your response!
Warm regards,
[your name]