I have three servers running sendmail as an MTA: mail.example.com, alpha.example.com and bravo.example.com. The first one, mail.example.com holds the email for users and provides IMAP service, for recipients other than example.com it sends to an ISP MTA.
I want scripts on alpha and bravo to be able to send email alerts to joe@example.com that joe can pick up in his regular email using IMAP from mail.example.com.
How do I configure sendmail on alpha and bravo to send mail to joe@example.com to mail.example.com rather than to joe's account on the sending machine?