"How can we change rules when we do not behave as mature individuals. I am very disappointed."
Qatar Airways - which employs over 31,000 people, is the world's tenth largest airline with a modern fleet of over 100 aircraft.
It is also one of the fastest-growing airlines in the world, investing in both the double-decker Airbus A380 planes as well as the ultra-modern A350 XWB, which was unveiled in December last year.
The airline has high expectation of staff, particularly as it operates out of the Muslim country, which does not allow the consumption of alcohol among Qatari citizens.
Qatar Airways told MailOnline Travel the email was sent to remind staff how they need to respect Qatari customs.
A spokesperson said: "The email was sent to impress on our cabin crew that, to make their working environment as good as it can be, while still respecting the norms and values of the Qatari society in which we work, everyone has a part to play.
"In Doha, the consumption of alcohol is not permitted for nationals and, although drinking is permitted for foreigners, being seen to be drunk would be considered highly disrespectful - it would have negative implications for both the individual and those associated with them."
The spokesperson added: "In this particular case, the individual concerned was found in a state of incapacity by the entrance of a Qatar Airways staff building.
"The vast majority of our cabin crew would themselves be disappointed at the idea that one of their colleagues should get into this situation, since they share our pride in the reputation of our team, and they would also, as we are, be very concerned about the safety implications for someone in this position."
Referring to Mr Dimitrov's comment in the email about 'changing the rules', the airline commented: "For over a year we have been working on a review and revision of the employment conditions for our cabin crew members, leading to reforms in our practices that have been universally welcomed by our staff as we have rolled them out since December 2014.
"This is something of which we are proud, but obviously we are making these changes in a culture which remains largely conservative. We think that the cabin crew community has an important part to play in showing that we have done the right thing in making these reforms, which is why we wanted to move quickly to highlight the kind of problems that could be caused by behaviour which offends local culture.
The spokesperson continued: "The matter is now under investigation, and we shall not be commenting further."
- The Daily Mail