This is because QR has the wrong settings in their SPF records in DNS:
user@shell ~ $ dig +short txt qatarairways.com.qa grep -i spf
"v=spf1 ip4:213.130.112.226 ip4:212.77.217.214 ip4:78.100.59.144 ip4:78.100.138.179 include:icpbounce.com include:sendgrid.net a:spf.vibe.travel a:web2.sniperhire.net ~all"
user@shell ~ $ dig +short txt qmiles.com grep -i spf
"v=spf1 ip4:213.130.112.226 ip4:212.77.217.214 ip4:78.100.59.144 ip4:78.100.138.179 ip4:12.130.153.25 ip4:12.130.154.100 ~all"
...if that only said "-all" at the end and not "~all".
This brought to you by the same gang of people that disables using passord managers with their website. Clots.
-A