chat.akaunting.com Verification Email not Received

I can't say I know what's wrong as I don't see anything wrong on the client side (status code 200), however when trying to sign up to chat.akaunting.com with a Tutanota email address (ie @tuta.io) no verification email is received.

I was planning to report this to MatterMost, but I found that Tutanota email address work perfectly fine on community.mattermost.com instance, so the issue appears to be with this instance of MatterMost.

I signed up with a Gmail address instead which worked on first try, however still unable to receive a verification email to my tuta.io email address.

Hello,

Emails are sent by SendGrid service so you should make sure there is no problem with domain reputation.

Regards

Could you please elaborate with why I should verify if there's a problem with domain reputation?
Would that not be concern of the administrator of the chat.akaunting.com instance?

I would try test receiving the email for app.akaunting.com as well, through the invoice menu, however I'm still unable to access my dashboard due to the 500 internal server error, so I'm incapable of testing this.

Tutanota is a reputable email service, and the email address works perfectly fine on all other websites, including the official MatterMost community server.