If you are going on a vacation or won’t be replying to the emails for some time, Gmail Vacation responder is a handy feature to sends an automated reply to incoming messages.
Gmail vacation responder is just the same as Out of Office assistant of Microsoft Outlook - emails that are marked as spam or addressed to a mailing list you subscribe to will not receive this vacation response from Gmail.
If the Gmail vacation responder feature is not working for you, Google Groups has a solution:
Type some text in the Vacation Responder and disable that feature. Click save changes. Now again goto Gmail settings and enable the vacation responder. Save changes again.
Alternatively, wwitch your Gmail language to English (US), execute the above procedure, and switch your Gmail language to what it was before.