XF 2.1 This message seems dangerous

[Xyphien]

Someone was trying to confirm their email on got this message. The website is new, and is geared around Homemade Trading Card Games. I'm not sure why this is happening other than the fact that the email is your standard xenforo email. How would I got about ensuring that this doesn't happen for other people?

 

[Lukas W.]

It's not really related to the content of the email, which is pretty much just responsible for what type of warning is shown. That it's shown in the first place probably relates to some incomplete mail/domain setup. Here's a small explanation on stackexchange regarding that.