gmail > smtp送信 > Username and Password not accepted. Learn more at\n5.7.8 http://support.google.com/mail/bin/answer.py?answer=14257 sh5sm32272477pbc.21 - gsmtp'

c++ builderにてgmailでメール送信テスト中にタイトルの問題が発生した。

The point is this: https://www.google.com/settings/security/lesssecureapps

You should change the "Access for less secure apps" to Enabled (it was enabled, I changed to disabled and than back to enabled). After a while I could send email.