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I am managing a postfix+dovecot mail server with a few hundred email accounts. We are doing our best effort to filter spam and viruses in inbound as well as outbound emails. Nevertheless, it happens several times a year that a series of spam messages originate from our server. In most cases this happens because of an infected computer from one of our users, maybe some not-too-secure form on one of the web pages, or the password of one of the users is somehow hijacked (phishing or such).
Usually this is quickly detected and stopped and the system protected but the problem arises because our IP address also gets quickly listed on some RBL lists where we have to request a delist. Some lists take a few days to delist IP and in the meantime we get a lot of complains from other email users that they can't send their emails to certain addresses.
Is it possible to configure postfix to forward this mail to another server with another IP address when an email is rejected due to IP blocking so another server could try to deliver it? How can I configure that kind of outbound email routing via two or even more servers?