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Our company recently enjoyed an Internet outage that lasted roughly 48 hours. Since we host our own email on SBS 2008 using Exchange 2007 (same server), we were unable to send and receive email throughout the outage.

I started wondering how many emails that customers tried to send us eventually timed out and produced return failures. This led me to several somewhat-related questions.

  1. How long does Exchange 2007 hold email in queue while trying to contact the remote server?
  2. Is there some place I can adjust these settings?
  3. As a best practice, roughly how long and how often should an email server try to send an email to a server that cannot be reached?
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up vote 2 down vote accepted

By default, Exchange 2007 will queue messages for a maximum of 2 days.

You can adjust the retry intervals, message expiration, and notification settings on the Limits tab of the server properties under the Hub Transport node of the Server Configuration node.

The default settings probably are best practice, otherwise MS probably wouldn't have made them the default.

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Further to this, you won't be able to tell how many customers got bounce backs, and nothing on your side will help as you don't control the settings on a customer site. Having a backup MX is cheap these days and most ISPs or webhosts offer the service. – Ryaner Apr 29 '11 at 20:04
Thanks for mentioning the backup MX, Ryaner. That's something I was wondering about. – HK1 Apr 29 '11 at 21:04
Simple linux box with SMTP software + config for forwarding emails to main MX will definitely help. Will cost less than 20$/m – Vick Vega May 1 '11 at 16:28

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