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Mark_und_Pfennig

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Hello,

I just evaluate the Kerio Mailserver and I have two questions:

1. I get SPAM which goes to nonexisting address and because of this bounces back. Now the sender is not a valid address / domain and so this mails stucks in the message queue with "Cannot connect to remote host" or "Service not available" and so on. Could htis be handled in a way that these mails never bounces or trys only one to bounce and then deleted from the queue without changing global settings and affected other mails?

2. In some domains I do a SMTP-forward if user not exists. The forward goes to another server on another physical machine. Problem is that this server could only handle 2-3 simultabous incomming connection. If Kerio now tries to relay more the 3 messages at one time I get "Too many connections" from remote side and the relaying delayed. Is there a way to set max. number of delivery thread for one domain?

Thanks

Stefan
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sedell

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keksforscher wrote on Tue, 02 September 2008 20:40


1. I get SPAM which goes to nonexisting address and because of this bounces back.

This sounds like a configuration issue. The server shouldn't be accepting mail for non-existent addresses. If the address doesn't exist, the server should not accept the mail during the delivery process, and there is no mail received to generate a bounce.

Scott
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Mark_und_Pfennig

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Hello sedell,

to 1. please let me give some details:

I have a domain (example xyz.de) for which I defined no users. Intention is that all mail to this domain is forwarded to another domain (SMTP Mailbag Delivery). For that case I can't test if there is a valid recipient. Now I have a spammer wich send to asjlhasdj<_a.t_>xyz.de and gives as sender-address ldsfjjhu<_a.t_>somedomain.com. I no get a bounce and the mailserver tries to deliver the bounce to ldsfjjhu<_a.t_>somedomain.com which causes the error.

The primary configuration aim is that my mailserver should between the sender and the other mailserver to do some processing.

Any suggestions?

Stefan
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ccjwells

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I think it is a problem with the downline mailserver that you are relaying to. We have a similar situation where we forward certain addresses on and when the next server sends a bounceback, it gets sent to us (since we relayed it) and then proceeds to get stuck in our queue.
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sedell

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If by mailbag delivery, you mean backup MX server, then this is normal and you have to live with it. It accepts all mail for the domain, and has no way of knowing what addresses are good or not good. When the server tries to deliver to the main mail server with the mailboxes, invalid addresses can't be delivered and generate a bounce. That's the problem with accepting mail to all addresses - without a way to verify the destination addresses, you generate a lot of bounces.

When spammers are involved with fake return addresses, you end up with a lot of mail sitting in the queue. If the faked domain is valid, the server tries to deliver to the domain. If there actually is no mail server at the faked domain, KMS has no way of knowing that. If it can't connect, it assumes the mail server is down, which is a temporary error, and re-queues the message for later delivery when the "down" mail server will hopefully be back up. The messages will sit in the queue periodically retrying delivery until they expire.

Scott
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Vladyslav

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I would be very pleased if you will share with me what are the technical limits for Kerio to send messages per day. Is it possible to send more then 50000?
Thank you very much.
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