Dear Sir,
I am a DNS expert, G Suite Reseller and specialise in solving these kinds of problems with email delivery to spam folders. Should you accept to assign the project to me I will need 1 to 2 days for delivery plus 1 day for DNS servers to propagate, hence this project cannot be guaranteed to be delivered in 1 or 2 days as stated by the other candidates!
I will need access to the DNS server of the domain in question and maybe to the hmailserver itself, but I will know after we get started. Other alternatives is using TeamViewer or if you can follow instructions and make the changes that is fine with me as well.
Waiting for your response.
Kind Regards,
/Fotios S.