553 Relaying Disallowed. Cant find any way to fix this issue.

553 Relaying Disallowed. Cant find any way to fix this issue.

On my account, I have set up mail hosting, MX Records and SPF, yet when I send an email to my account I get an error saying "553 Relaying Disallowed". I have followed a number of guides, and combed through this forum for any sort of help but I've followed everything and yet the problem still happens.

One thing I find is for a short time after applying some settings, I can receive emails for a few minutes, and then things go back too getting the 553 error. I even phoned technical support, and I manged to configure stuff and the problem seemed to have fixed itself as the email remained contactable for a while, but trying it out earlier today I've got the error.

It's really frustrating because i just can't seem to find a permanent solution to this error. Please can somebody help me out with this.