As it turned out, JavaMail supports the search using the Cyrillic alphabet. I've tested Ukrainian, Outlook and Yahoo providers. All works fine using such email providers. But the search using the Cyrillic alphabet doesn't work on Gmail.
Also, I've created a new question on stackoverflow.com JavaMail. IMAP Search using a literal on Gmail. Short details: the search using the Cyrillic alphabet doesn't work on Gmail because JavaMail automatically send s the command K2 ENABLE UTF8=ACCEPT and later use a wrong command to search a text with the Cyrillic alphabet.
As it turned out, JavaMail supports the search using the Cyrillic alphabet. I've tested Ukrainian, Outlook and Yahoo providers. All works fine using such email providers. But the search using the Cyrillic alphabet doesn't work on Gmail.
Also, I've created a new question on stackoverflow.com JavaMail. IMAP Search using a literal on Gmail. Short details: the search using the Cyrillic alphabet doesn't work on Gmail because JavaMail automatically send s the command
K2 ENABLE UTF8=ACCEPTand later use a wrong command to search a text with the Cyrillic alphabet.