Not sure if this has anything to do with Netlify but one of my clients is complaining that their emails are going into spam when replying to the Netlify form submissions.
I know it may be their client’s email spam filter, but my client says it’s happening frequently. Is there any solution that I may have overlooked?
Hiya, sorry your client is having trouble getting your forms to work.
This Support Guide is the first port of call to debug any forms issues. Please start here and work through these resources!
We also recommend trying to search the forums or look at topics tagged Netlify forms if you haven’t already - it’s likely your question was already asked by someone else!
If you are still having problems, please provide more information such as what you have already tried, a link to your live form, your form name as it exists in the UI, etc. 
Thanks!
Hi there,
I’ve started searching the forums because I was experiencing the exact same issue, more specifically, when replying from the Gmail account I’ve been notified on to users who also submitted a Gmail account. However, removing the Netlify prefix from the subject line seems to have fixed the problem.
I’ll reply again if the problem reappears or if I realize it affects e-mail providers other than Gmail.
thanks for sharing! 