In the email, seen by Campaign, Courtier describes "30 meetings, a week in a hotel basement in Luxembourg, five weekends, an unknown number of all nighters," which took place to secure the Vodafone business for the WPP network agency, adding that "local markets" had been "absolutely key" to the win.
Courtier said: "Our success is a massive testament to the strength of our network and the collaboration and cooperation we demonstrated with our partners at WPP’s Team Red, Maxus India and all across GroupM", and described how "everyone stepped up and delivered" worldwide.
Although he said there are "too many people to thank", Courtier reserved special praise for what he describes as a "core team" of GroupM senior management and the "fantastic new business and marketing team" who "divided and conquered in order to fulfil every obligation with energy and passion".
Yesterday (10 April) Campaign broke the news that Vodafone had awarded its global media planning and buying account to Group M's MEC, with the UK account set to be run through a 'Team Red Media' unit.
Omnicom network OMD was the incumbent on the global business, but had been knocked out of the review process in March.
In the UK, Vodafone spent £47.4 million on media in the year to 30 September 2012.
Vodafone retained OMD to the global media planning and buying account after a review in August 2009, when the business was understood to be worth £800 million.
Vodafone also works with local media agencies in some markets. OMD had retained Vodafone as a client for 17 years, except for a six-month period in 2009.
"So many people across the network have touched this review either directly or indirectly," Courtier said.
The Vodafone win tops off one of the most successful weeks in WPP history, as MEC in the UK also landed the £110 million media planning and buying account for BGL Group, the owner of Comparethemarket.com, after a head-to-head pitch against incumbent ZenithOptimedia.
MEC sister agency Mindshare also picked up the £60 million UK media brief for high street retailer Marks & Spencer snatching the account from incumbent Walker Media after a closed pitch process.
Speaking of the Vodafone win in his message, Courtier encouraged his network to "celebrate big".