M2M has held the business since 2006, when it took the account from Vizeum in a pitch that also included Mindshare and Starcom MediaVest Group.
The chain is understood to be leading the review from its headquarters in Barcelona and has contacted selected agencies for chemistry meetings. It is not known whether M2M is repitching for the business.
Last year, Scarlett Johansson replaced her fellow Hollywood actress Penelope Cruz as the face of Mango and has completed three campaigns for the retailer.
Mango, which is owned by the Spain-based Punto Fa textile group, opened its first store in 1984.
The retail chain now has nearly 1,500 outlets in 92 countries, with around 20 based in the UK.