While this doesn't seem overly important at first glance, the content your prospective partner provides can be a very important clue about their approach to your brand and the email marketing challenges it will pose.
If an agency's content is stale, outdated, and just not of very good quality, you might want to move away because they either don't care to share their knowledge with you, or they can't be bothered to work on their image, something a serious marketing agency would never do.
Do they consistently offer internal assets (eBooks, blog posts, webinars, etc.) that convey their thought leadership and expertise? Externally, do they contribute to industry publications and share helpful industry-related insights? Do they present at industry events? Are they maintaining their social media platforms well? If so, it is very likely they will take good care of your business, too.