On 23/11/2010 17.37, Noel Jones wrote:
On 11/23/2010 5:54 AM, Angelo Amoruso wrote:Hi,is there any way for postfix to change the outgoing relayhost using a sort of policy server?Postfix doesn't directly support that, although there may be workarounds for some situations. What information will you use to determine the relayhost? What's the application?
Thanks for answering.One situation is when having Postfix using as smarthost your ISP smtp server. Nowadays the smtp server DNS record is actually a round-robin dns name or set of aliases which points to a pool of smtp servers.
Example: smtp.n3bula.com resolves to: 62.149.128.202, 62.149.128.203, 62.149.128.200, 62.149.128.201Happens often that one of more of the ISP server which the name resolves to is being listed in some RBL blacklist. And then you've a strange scenario: some emails get through and get delivered, some bounce remotely at destination 'cause the server blacklisting.
Which, warning and error messages apart, gives some headache to users.What I'd to accomplish is checking if the smtp server I'm about to delegate the outgoing mail is blacklisted (using a defined list of rbl providers) if not, trying the next ip address (if any), otherwise wait and do it again.
One very-raw-and-unelegant way - keeping the email inside the Postfix queue - would be having such detection process outside postfix on a special program, which would do the checks periodically and then update the main.cf configuration file accordingly.
Hope my explaination (and my English ;-)) was clear enough; otherwise feel free to ask more details, I'd be pleased to provide more.
Angelo
