Firebase Authentication: Emails sent but not received on special email addresses such as *@gmx.at

Issue

I am using Firebase Authentication in my Ionic App. Some users have reported to not receive the verification email which is sent after a user signs up, or when the resendVerificationEmail is triggered.

This works fine for email providers like @gmail.com or @live.de, but for those other users with special providers like @gmx.at it's not working. The emails are sent successfully according to firebase but they are never received.

Possibly the emails get filtered? Has anyone else ran into this problem? The message template can not be modified but would using a custom SMTP server possibly help?

Solution

The problem is solved by using my own private SMTP server for sending the Authentication emails.

I am using a hosting service for my domain that comes with email service so I am using that one. Using other services such as Mailgun or Mailjet etc. might also solve the problem.

You can set up your custom SMTP server right in the firebase console under Authentication/Templates.

Answered By - bergben