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SOLVED Subscriber sign up mail issue for Ghost 3.0 instances on a sub domain

  • Seems to be an issue with a Ghost 3.0 instance sending subscriber magic link emails to users when signing up on a Ghost instance on a Cloudron sub domain. Ghost assumes the domain it should be sending from should include the sub domain e.g., when the blog is at

    The sign up form returns "Please enter a valid email address!" but the logs show the following:

    "Failed to send email. Reason: Mail from command failed - 550 Authenticated user cannot send mail as"

    Having Email Masquerading enabled for doesn't make any difference. Sending a test email from the Ghost UI works fine as the email comes from and I'm guessing doesn't encounter the authentication error.

    The Ghost UI doesn't offer the ability to alter the domain part of the sending email address. Is this something that can be modified within the Ghost package for updating / new installations? Also what would be the best temporary solution?

  • Staff

    @tkd Maybe this is a bug in the packaging. Ideally, the Ghost app should know out of the box from which domain it's sending emails from. Let me investigate and get back on this.

  • Staff

    I am able to reproduce the above. It seems that the part is hardcoded at which is in turn computed from the location where ghost is installed

    I am not sure what the fix is. Do you know why Ghost is not using the mail settings it already has in it's config? (Sending normal member invitations works as expected).

  • Staff

    @tkd Sorry. forgot to give the workaround. I have given explanation of the workaround below.


    • Add a Domain called in the Cloudron Domains view. This can have the same DNS settings as
    • Now go to Email view and enable masquerading for
    • Then change the domain of your existing app installed at i.e in configure UI -> Location and then in the drop down select and leave the location field empty. Effectively, the app remains at but is using the settings of the Cloudron's

    On Cloudron, we don't allow apps to send email with arbitrary addresses across domains. So, if an app has to send emails as then it has to be installed under that domain.

    Side effect:
    Now your invite emails will also go from Hope this is OK. BTW, you can change this "" in the Email section of the app's configure UI.

  • Staff

    A late note but in recent releases you can now have the email set to a different domain from where ghost is hosted.

  • @girish Just tested this workaround and it works!

    (I set DNS to Manual to save creating another API key and DNS records since the sub-domain is only for development).

    There seems to be some typos in the instructions above though between and that might be worth fixing to help anyone else searching for a solution on the same too.