Replies to contact form entries going to spam

My client is using the plugin on her site, and told me that pretty much every time she replies to a contact form entry it goes to spam for the person receiving the email. I’m guessing that this has to do with my client’s host (since she’s using a custom email address), but I was wondering if there’s anything I can do on the website end to keep the emails from going to spam?

https://www.ads-software.com/plugins/contact-form-7/