What all language components will have to be used for implementing an email service system using java?
If you want to implement an email server (SMTP, IMAP, POP3) - there is already Apache JAMES. It's open-source, so you can look into its sources if you insist on making one.
If you want to just send emails, having an already installed SMTP server, then use Simple Java Mail or commons-email. Both sit on top of Jakarta Mail (previously JavaMail) and are very developer-friendly.