Is there a solution for 550 User Unknown mails
This is perhaps off topic, but all machines in question are running FreeBSD :) Every day I get dozens of failed email notifications in the form of: UNDELIVERABLE MAIL Your message to the following recipients cannot be delivered: [EMAIL PROTECTED]: webmail.hansenet.de [213.191.73.2]: RCPT TO:[EMAIL PROTECTED] 550 RCPT TO:[EMAIL PROTECTED] User unknown This user Unknown message is due to my server rejecting a mail to my domain (my domain is not alicedsl.de) for an Unknown user. Doing some reading, it appears that in a perfect system where there is only 1 email server per domain, I won't recieve these messages since during the whole email conversation I will tell the person talking to me that I don't know of that account and no extra email is generated. With secondary mail servers, I am accepting mail for other domains, and then forwarding them on. It is my belief that acting as a secondary mail server is what is causing me to receive all these errors. What I believe is happening is that for whatever reason the spammer is talking to my email server for a domain I am secondary on. I accept the mail and finish the conversation. I then talk to the main email host to let them know of the email I got for them. The master host responds with 550 User Unknown as it should. Being the good little secondary email server I am, I try to respond to the sender that they got the wrong address, which turns out to be fake. Assuming that my guessing is correct, is there any way to stop this flood of reject emails short of not being a secondary server for anyone? If my guesses are incorrect, then what is actually going on and how do I stop the flow? ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Is there a solution for 550 User Unknown mails
Derrick Ryalls wrote: [ ... ] With secondary mail servers, I am accepting mail for other domains, and then forwarding them on. It is my belief that acting as a secondary mail server is what is causing me to receive all these errors. What I believe is happening is that for whatever reason the spammer is talking to my email server for a domain I am secondary on. I accept the mail and finish the conversation. I then talk to the main email host to let them know of the email I got for them. The master host responds with 550 User Unknown as it should. Being the good little secondary email server I am, I try to respond to the sender that they got the wrong address, which turns out to be fake. Assuming that my guessing is correct, is there any way to stop this flood of reject emails short of not being a secondary server for anyone? Your assumptions are basically right. The best way to deal with this is to make the secondary MX you run aware of which email addresses are valid and which are not, so it can reject misaddressed mail rather than accepting it and then having to bounce it later. Setting this up via LDAP, NIS, or whatever might be possible but it typically is difficult. Intermediate solutions include using greylisting or creating a manual blacklist of frequently-spammed invalid accounts which you reject immediately. -- -Chuck ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Is there a solution for 550 User Unknown mails
Derrick Ryalls wrote: This is perhaps off topic, but all machines in question are running FreeBSD :) This problem is related to the configuration of your MTA, not FreeBSD. Every day I get dozens of failed email notifications in the form of: UNDELIVERABLE MAIL Your message to the following recipients cannot be delivered: [EMAIL PROTECTED]: webmail.hansenet.de [213.191.73.2]: RCPT TO:[EMAIL PROTECTED] 550 RCPT TO:[EMAIL PROTECTED] User unknown [...] With secondary mail servers, I am accepting mail for other domains, and then forwarding them on. It is my belief that acting as a secondary mail server is what is causing me to receive all these errors. [...] Assuming that my guessing is correct, is there any way to stop this flood of reject emails short of not being a secondary server for anyone? Which MTA? In Postfix, you can use the relay_recipient_maps parameter to query a list of valid recipients. The MX for which you're acting as secondary should be able to provide the list. -- Sahil Tandon [EMAIL PROTECTED] ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
