Error 553 relaying disallowed problem

Error 553 relaying disallowed problem

I’m really disappointed with the level of support for this error to be honest… a quick search of these forums and I can see that lots of other people have had the same problem but I need the help of your support team to fix it and despite sending emails, filling in support requests and making multiple phone calls (wherein I have to leave a message because “all of our operators are busy”) I’ve had nothing back…

I suspect the issue is my domain expired for a couple of days and was renewed, which means apparently that it needs to be reverified as it seems others have faced in the past… but because the domain is showing as already verified in the admin console I can’t generate a cname record or txt record to verify it. 

Right now I’m receiving emails as normal but completely unable to send emails… it’s soooo frustrating as I need my email right now and it’s potentially costing me a huge amount of work. 

Please can someone help with this!