Very often, a huge amount of sensitive data is stored in users ‘ mailboxes-from documents sent by HR for the device to work, and ending with photos and letters of personal content that can be used for blackmail. However, do not forget that today a personal mailbox is used for registration in social networks, remote banking systems and is used to recover registration passwords in case of their loss. Thus, gaining access to the mailbox opens up a wide range of opportunities for an attacker to not only read personal correspondence or find out the password from a social network, but also in some cases steal money from a bank account. Password brute force is performed by automatic brute force and most often by a dictionary that includes the most common combinations. This means that for secure use, the password must meet certain requirements: be reasonably long, contain uppercase and lowercase letters, numbers, and special characters.