Becky! is an e-mail client developed by the Japanese company RimArts from Matsudo City, Chiba. In the early 2000s, it had received attention in East Asia due to good support for CJKV characters. It supports multiple accounts using the standard POP3/SMTP or IMAP protocols, with or without SSL, including the APOP security feature, and supports PGP encryption. It also has support for large number of plugins; one such plug-in offers Hotmail access, another offers Usenet newsgroups access.

Version 2.05 of the program was included in two 2004 round-up reviews in German magazines. PC Professionell (the German counterpart of PC Pro) ranked it 11th out of 14 email clients tested. PC Direkt found it "insecure", and that it imitates Outlook design, but remarked that it can send voice messages.

A buffer overflow vulnerability is known to affect all version of Becky! before 2.50.