Can not deliver mail to or - 421 Message rejected

Posted on 2009-02-18
Last Modified: 2013-11-16
Hi All,

I am having trouble sending messages to some of our customers who have bigpond accounts
I am aware of at least 5 accounts at bigpond that we regularly have a problem with.

Below is a sample from the server log.

 SMTPClient: MAIL FROM:<> SIZE=14348
 SMTPClient: RCPT TO:<>
 SMTPClient: End of pipelined commands
 SMTPClient: ReceiveResponse: 250 Sender <> and extensions (SIZE=14358) Ok
 SMTPClient: ReceiveResponse: 250 Recipient <> Ok
 SMTPClient: ReceiveResponse: 354 Ok Send data ending with <CRLF>.<CRLF>
 SMTPClient: Data Send Succeeded 12217 bytes
 SMTPClient: ReceiveResponse: 421 Message rejected
 SMTPClient: Attempting to Disconnect:
 SMTPClient: CommandQUIT:
 SMTPClient: Connection terminated with status: 2562
 Router: No messages transferred to BIGPOND.NET.AU (host via SMTP

The message retries a number of times and just occasionally will get through, but mostly will go back to the sender as rejected.

I tried calling Bigpond, but as my account is not with them (only the receiving user) they would not help me.

Any suggestions on how to fix would be appreciated.

Question by:Gary_Brown_Applied
    LVL 4

    Expert Comment

    Sounds to me like bigpond doesn't like your mail server. They have implemented some changes in recent years to reduce spam. Im not sure exactly what they have implemented but i would guess that greylisting is one of them.

    Greylisting is when the recieving mail server does not make a connection with a new host straight away. It usually gives you a message like "try again later" or if the admin of the server is thoughful enough "This server usues greylisting to help reduce spam - please try again withing X minutes". Usually this is quite a low figure like 3 or 4 minutes. If you try to resend after this timeout period the message will be accepted and usually your address placed in a whitelist for a certain period of time.

    Also, it could be a number of things combined... like if you do not use SPF (sender policy framework). SPF is a zone record you add to a domain, which advertises the address of your sending mail server/s so if the IP in the mail header doesnt match, it will fail the test and either be rejected or marked as spam (according to the admins own policy). Configuring SPF isn't a bad idea.

    An online resource i like to use is . It has a great blacklist checker and other diagnostic tools.

    Also, having a static ip for your mailserver is a good idea too (im sure you probably do) but also having a generic PTR record for your ip can also cause you to be listed (i.e . To resolve this you can call your ISP to have this done for your IP (make it revsolve to - or as appropriate)

    Fixing a few of these issues could lead to the spam system in place at big pond not scoring your incoming mails so high as to get your mail server removed from any blacklists on their server.

    Hope this helps, if you need any more info just ask.

    Author Comment

    Checked mxtoolbox and we are not on blacklist
    Yes we have static IP address

    This is the response I get when I do a SPF check.
    Prefix Type Value PrefixDesc Description
    + a   Pass Match if IP has a DNS 'A' record in given domain
    + mx   Pass Match if IP is one of the MX hosts for given domain name
    + include Pass The specified other domain is searched for an 'allow'.
    ? all   Neutral Always matches. It goes at the end of your record.  
    v=spf1 a mx ?all
    Does that all look right??

    LVL 4

    Accepted Solution

    Yes it seems fine. Have you tried changing your retry intervals to, first retry 4 mins, second, 10 mins and see if that helps incase its a greylisting issue.

    Personally i hate grey listing. Its completely pointless...
    LVL 63

    Assisted Solution

    Have a look on

    This should give you more info on your domain.

    maybe a reverse DNS PTR issue.

    I hope this helps !

    Author Comment

    I have check all our setting as per suggestions.
    Still no real resolution to this problem, but thanks for your input. I will just have to put it down to a Bigpond 'thing'

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