Not receiving emails from 1 specific company

Hi,

I have both an @icloud.com and @gmail.com email address and I am not receiving emails from 1 specific company which is East Midlands Airport in the UK. These emails are mainly to confirm bookings made for car parking at the airport and also promotional emails from them to offer money off car parking.

I have added the email addresses they use to my Contacts and checked that nothing is set up to block or direct the email to another folder, or going into the spam folder. I have also checked with customer services at the airport that all is OK with my account at their end and accessed my gmail email account via the web, but no emails from East Midlands. Everything was working fine up to October/November last year.

My ISP is BT internet and I have also contacted them for advice but they seem unable to help - or do not understand my question - and keep referring to BT Internet email accounts.

My question is, do my @icloud.com and @ gmail.com email addresses go through my ISP (and the emails are possibly falling foul of their spam filters) or do they somehow bypass the ISP spam filters because I am not using a @btinternet.com email address?

thanks

Kel