I think the problem is SMTP not working with CloudeFlare and Zen Cart waiting for email sending, this cause timeout and if the customer refreshing the page or clicked again the confirmation button the orders are duplicating.
What is the correct setting for MX and mail server to work SMPT correctly?
I know CF not provide SMTP service. Our hosting provider is Hostgator and there is the mail server.
The question what is the correct settings for mail and MX to work SMTP correctly.
Hostgator works. The settings there probably correct. I asked the Hostgator support to check that and they tell me everything is ok on their side.
Name TTL Type Record
olaszsped.com. 14400 A 192.185.5.87
olaszsped.com. 14400 MX Priority: 0 Destination: olaszsped.com
mail.olaszsped.com. 14400 CNAME olaszsped.com
olaszsped.com. 14400 TXT v=spf1 +a +mx +ip4:192.185.4.64 ?all
The quetion what are the correct CloudFlare settings.