Postbox  is quite a convenient mail client, which is built on the basis of Mozilla Thunderbird, which is why it resembles it so much, however, according to the developers, they have more functionality. It should be noted right away that the client can be convenient for those who often write letters with attached files, such as photos or documents, videos, and so on. You can send photos to you directly from the client interface, and then you can immediately upload them to the Picasa service, you can download Postbox below.
I would also like to note the convenient tab bar, there is a set of special buttons, for example, Images, Links and some others, they can allow you to open all attachments in a letter with one click of the mouse, you can also open all links in separate windows. Plus, you can be able to perform the set of actions that you need more with each attachment in the letter.
Postbox has its own search engine, you can instantly find the information you need in letters sent to you, for example, the name of a contact or his mailing address, the link or picture you need, any piece of text. After the search is completed, its results can be viewed in a special form. Postbox is easy to use, Russian support is available, I really liked the interface, no complaints