The Finnish mobile phone giant said the service, which was launched in December last year, was originally inspired by the growing number of people who don't have access to a PC.
Tom Furlong, head of consumer messaging at Nokia, said: "More than just reaching a company milestone, this proves to us that there is a real appetite in the developing world for these types of tailored services.
"For first-time email users, Ovi Mail provides a digital identity and we are thrilled by its rapidly rising adoption rate."
Part of its success will also be down to its no-cost, easy out-of-the-box set up, and its support for numerous handsets including the 2330 classic, 2630 and 5310.
Mobile email was first popularised by Research in Motion's BlackBerry devices, and the latest subscriber figures from RIM of more than 28 million show the likes of Nokia still have some way to go to catch up.
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