Unfortunately, Heart Internet shuts off email delivery if you make any changes in your domain's MX records.  This is unfortunate, since it breaks most spam filtering services, including SpamHero.   Even if you try switching your original MX records to a lower priority, their service still refuses to accept email. 

If you have tried to enable SpamHero before seeing this note, you should be able to switch your MX records back to their original settings and then re-deliver the failed deliveries through the SpamHero control panel.

If anyone is able to successfully get Heart Internet working with SpamHero, please let us know how you did it so that we can update these instructions.