How to check MX records?

If your domain uses the Gandi LiveDNS:

Go to the Domain Name / DNS Records menu and check the presence of: 

@ 10800 IN MX 10 spool.mail.gandi.net. 

@ 10800 IN MX 50 fb.mail.gandi.net. 

otherwise add them. 

If your domain uses GANDI classic DNS (a,b,c)

 In the Domain Name / Name Servers menu, switch to Gandi LiveDNS

 If your domain uses external DNS 

Contact your DNS provider for more information, or check from this site (choose NS): 

https://www.whatsmydns.net/ 

The result will tell you which mail servers you are using.