AquaMail

A worthy alternative to the standard e-mail client Android. In addition to supporting three popular protocols, AquaMail has its own engine, which is capable to work with all popular e-mail services.
Among the competitors this client has a wide list of options for customizing the interface, which in turn has a completely Russified view. It is also worth noting the presence of widgets to the desktop, they are able to display the number of new messages.