Why is some mail to my mail server delayed?

To help combat large amounts of Spam, all maximumasp Hmail servers run greylisting.


Grey listing allows you to prevent spam by temporarily rejecting email to your server. Grey listing benefits from the fact that properly configured email servers will try to resend messages later, while spammers normally will give up immediately if your server rejects an email.


When a sender tries to deliver a message for the first time to your server, hMailServer will save the senders IP address, the senders email address and the recipient email address. This information is called a triplet. hMailServer will reject the message and kindly ask the sending server to retry later. The next time the sending server tries to deliver an email which matches the triplet, hMailServer will accept the message.Most properly configured mail servers attempt redelivery within 15 minutes and have a set  number of retries as well as retry intervals. 


If a sending mail server receives a 450 temporary rejection error code, it is required by Internet standards to retry sending the message. We can't emphasize this enough: any mail server that does not retry the message is not sending mail properly and will be unable to properly deliver mail to any recipient who is using greylisting.


We have opened the ability for domain administrators to disable this feature via the Web Admin interface accessible at if you believe this filtering is blocking legitimate messages. We have also implemented whitelisting for known ISP's and other major mail sources who may not properly process  greylisting responses.

The following KB article provides you with information regarding disabling greylisting for your domain.

Article ID: 530, Created On: 4/20/2007, Modified: 6/9/2009

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