Flexible vacation responder using procmail

I wanted to have a vacation response to business mails while on holiday, while letting private mails untouched.

• Main account is user
• Create a second mail account on the server, user_o
• Create a .vacation.msg file with the response
• Create a .procmailrc file

:0:
* ^((Delivered-To:)|(From:)|(To:))((.*domain1\.ch)|(.*domain2\.com))
{
  :0 c
  | /usr/bin/vacation -a firstname.lastname user

  :0
  ! user_o
}