Dear Sir/Madam

Dear Sir/Madam

thank you for your e-mail.

I am out of the office on vacation from [date] until [date] and I will have limited access to emails.

For urgent assistance please use the following contacts:

[substitute name] [substitute email]
[substitute name] [substitute email]

If you need really urgent assistance you can reach me on my mobile number [telephone].

Thank you.

Kind regards