It may be entirely legit, but I would have issues with an email coming from the rnmk.com domain (or providing that as the principal email address for replies) on a matter relating to Easyjet, especially when
www.rnmk.com returns nothing, and a look-up of rnmk.com shows it to be controlled by a company based in Bozeman, Montana in the USA, outside the EU, and potentially breaching data protection laws
Outsourcing day-to-day tasks is one thing, but appearing to effectively disclaim responsibility for correspondence when a customer is about to be told that the supply of goods has been cancelled is not generally a good idea