Problem with mail delivery delay and godaddy

[Hizaky]

Hello, I have a problem I recently moved from my small domain to a Goddady VPS, before I changed everything worked perfectly with the emails.
But since I moved I've had complaints that the emails with the sold accounts take a long time to arrive, I've checked them and some arrive immediately, others take 10 minutes and others take hours.
I've hired this one: https://gyazo.com/17b0c2f419c1a1c96ad66c757488aa0d.png

Has anyone had the same problem or does anyone know how to fix it?

the prestashop version is: 1.6.19
I don't know if I should see it but the module that handles code delivery is Key Manager

Thank you very much.

 

PS:If I can't find a solution that is recommended by VPS that is good and that doesn't cause any problems with the sending of mail, since my site sends a lot of sales.