I would like to create a list of
default times that mail server will try to deliver email to other email server before it sends information
Unable to deliver back to sender (I mean temporary errors here like network down, server down, no connection, non permanent error messages from server).
I'm interested in broad spectrum of email solutions (possible clients) that may send us emails to write documentation before introducing Exchange 2010 in our network as a mitigation plan so that we could safely assume 8 hours downtime (in case of problems) won't cause any problems in terms of email delivery that management may .
An example I've found for GMail (not confirmed)
Gmail treats mail to bad domains as a temporary failure (because it may be caused by a DNS issue). It will warn you after 24 hours that it hasn't been able to deliver the message, then keep trying for two (if I remember correctly) days before sending you a final failure message.
I would be interested in default settings of multiple servers and widely available free accounts services. I do understand that some administrators may have tweaked the settings but this information would give me nice overview.
Just to add as a side note. I will have 2nd MX server and redundant solution and this information is to give an overview of crisis situation where everything goes down and we have to fix it. Don't want management to panic during time we fix it.