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Old 07-20-2006, 03:19 PM   #1
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Registered: Oct 2005
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HELP! POSTFIX Relay access denied

I am very new to POSTFIX- I work for an ISP - I have customer who needs us to catch email for him when his server goes off line a few min every hour. However, I always get a 550 Error on DNS Reports when I try and check with - The MX records are correct it does notice the other entry which is

I have read everything about RELAYING for the domain however - some places have me going creating relay_domains, some add under access - some have me adding info to my

I am so confused at this point. All of the correct information is in mynetworks **this is the one thing I do know.

I think I am looking for stepby step instructions that I can actually understand- If you need more info please let me know



Sorry I don't really have a clue.

Old 07-20-2006, 06:06 PM   #2
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If I understand your question, you want to act as a backup MX for

The DNS records for should contain at least two MX records similar to this:
Code:   8172    IN      MX       5   8172    IN      MX      10
Notice that the higher-numbered record points to the backup server. This will cause any mail destined for to go to in the event that is down.

There's not much that needs to be done on the ISP's postfix server to act as a backup for

relay_domains =
relay_recipient_maps = hash:/etc/postfix/relay_recipients
The first line makes tells postfix to accept mail for, but to hold on to it. Postfix will do an MX lookup on and deliver the mail to when it becomes available.

The second line defines all the valid recipients for (which avoids accepting mail for nonexist usernames, i.e. avoids spam).

/etc/postfix/relay_recipients might look something like this:
Code:         dummy          dummy              dummy              dummy              dummy
Hash tables require a value, so we put "dummy". In this case, the value is not used.

Finally, we build the .db file and reload postfix:
postmap hash:/etc/postfix/relay_recipients
postfix reload

Last edited by Berhanie; 07-20-2006 at 06:16 PM.
Old 07-21-2006, 07:15 AM   #3
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Registered: Oct 2005
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just a few more questions

I was wondering if I could
relay_domains = /etc/postfix/relaydomains
Just wondering because if I have several domains that I am relaying for.

Also do I need to know all of the email address' for in the relay_recipients?

Old 07-21-2006, 08:56 AM   #4
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Registered: Oct 2005
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Thanks So Much

Thanks I got it fixed the way I posted above worked! Thank you so much!!!


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