Dear [User's Name],

Thank you for your email.

I would like to inform you that our team supports only Application X. Since your request is related to Application Y, it has reached us by mistake.

I have now forwarded your email to the Application Y Support Team (marked in CC), who will assist you further.

If you need help with anything related to Application X, please feel free to contact us.

Best regards,
[Your Full Name]
[Your Designation]
[Team Name]