Most probably this is because your mail server thinks that MyTaskHelper.com sends you SPAM.

We’ve noticed it with the following mail server providers:

ukr.net
mail.ru
mailgate.freeparking.com
mx30.aha.ru

We contacted these services but had no responce at all.

Good news is that the most widely used emails work:
google.com
yahoo.com

So, we highly recommend you to use gmail or yahoo emails for MTH.

Hope it helps!