Mailing List Message #14911
From: Warren Michelsen <>
Subject: Re: Error 450 rejections
Date: Fri, 11 Feb 2005 09:03:56 -0700
To: Alan Munn <>, SIMS Discussions <>
At 4:20 PM -0500 2/10/05, Alan Munn issued a series of ones and zeros which decoded as:
>Hi, I run a mailing list using Macjordomo with SIMS as my mailer. For one user on the list, my outgoing messages get rejected as having an unverified sender address.  Although this is supposedly temporary, the user does not seem to get messages in a timely fashion.  Her ISP says that it a problem with SIMS.  Is there something I can do to fix this on my end?

Does your SIMS have an account named: mailinglist-request? It doesn't look like it. It sounds like their server tries to establish a connection to send to before accepting mail from that sender. It's an extreme anti-spam measure.

>Here is a sample reject header (I've changed the actual addresses.)
>> Failed to deliver your message to <users-address>:
>> SMTP: Address rejected by host
>> Host '' says:
>> 450 <>: Sender address rejected:
>> unverified address: Address verification in progress

I guess it all depends on how they 'verify' the sending address.

Check your SIMS log to see what they do when you try to send to them.
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