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Background and Frequently Asked Questions (FAQs)

Posts: 9,041
Thanks: 490
Fixes: 43
Registered: 06-04-2007

Background and Frequently Asked Questions (FAQs)

Comprehensive information on planned Email platform development and IronPort spam filtering, the first phase of that, is given in the blog IronPort & the Future of the Email Platform. More detailed technical information is given in the post Ironport & plans for the Email Platform 2008/2009 in the present forum.

A blog IronPort anti-spam migration FAQ can be found on the Community Blogs pages. That information is supplemented here. If neither source covers your question please raise it in this forum. Additional questions/answers will be added based on that feedback.

Support Questions
How is IronPort Migration support provided?
Support for Migration to IronPort is provided entirely through this forum, please do not raise a ticket.

General Questions
Where can I find a detailed explanation of what the IronPort headers mean?
There isn't a detailed explanation at the moment. The same x-pn-pstn: header is used for spam scoring though.
Is there a limit on white, black and safelist sizes?
Yes there is, around 500 addresses/domains per list.
Is there a difference between the Manage My Mail whitelist and the IronPort safelist?
No, they are simply different terms for the same thing. However adding things to the whitelist via Manage My Mail will add the same entries to the safelist on all mailboxes for the selected domain (or for all your domains if Apply these settings to all of my domains is selected). If you add entries via the IronPort interface this would work on a mailbox by mailbox basis.
Why do I no longer receive newsletter emails that I have subscribed to?
This is likely to be for one of two reasons -

  • The IP address of the sending MTA fails IronPort's SenderBase lookup (see next but one question). The only immediate solution to this problem is to disable anti-spam filtering.

  • You have Edge Protection enabled and the email is deleted as blatant spam. If this is the case then either whitelist the address (but see the next question) or turn the feature off.

Is it correct that whitelisting/blacklisting does not always work?
Unfortunately yes - possibly until IronPort release a new build of their software. The present situation is as follows (note: the situation for whitelisting applies equally to blacklisting). Problem 55215 has been raised to investigate which of these can be made to work with the present software:

  • Specific (non catch-all) mailbox - Whitelisting works.
  • Alias to a specific (non catch-all) mailbox - Whitelisting doesn't work.
  • Redirect to a specific (non catch-all) mailbox - Whitelisting doesn't work.
  • Alias to a catch-all mailbox - Whitelisting doesn't work.
  • Redirect to a catch-all mailbox - Whitelisting doesn't work.
  • Redirect to an external address - Whitelisting is irrelevant.
  • Catch-all address (excluding the above) - Whitelisting doesn't work.

Is there a way to check IronPort's view of a mail sender's reputation?
Yes, enter their domain name in the IronPort SenderBase Look up your network: box .
Where can I find discussion of spam scoring?
See the Spam Scores topic on this forum.
What happens to non-spam emails addressed to nonexistent mailboxes?
If catch-all is On they will be delivered to the default (catch-all) mailbox. If catch-all is Off they will be rejected and returned to the sender.
IronPort includes greylisting in its armoury - what is greylisting?
Greylisting is a way of coping with potential spam which involves temporarily rejecting a message from an unrecognised mailserver. Genuine senders will almost certainly try again after a variable time (often 15 minutes but it could be much longer) and it will be accepted then. (More details.)
Are senders notified if they send messages from an address on your blacklist?
If your blacklist entry is a domain e.g. then emails sent from it will be silently deleted.
If it is a specific email address e.g. then messages are refused with a 550 server response.

26/11/2008 Initial creation
27/11/2008 Additional questions
01/12/2008 Reference to Migration FAQ blog
23/12/2008 Add questions on list sizes and Whitelist/Safelist
24/12/2009 Add question on sender reputation checking
14/01/2009 Add question on Spam Scoring discussion.
15/01/2009 Add questions concerning newsletter receipt and whitelist/catch-all incompatibility.
30/01/2009 Add question on mail addressed to nonexistent mailboxes.
06/02/2009 Add question on greylisting.
14/02/2009 Update whitelisting/blacklisting situation question.
15/02/2008 Add question on response to senders on your blacklist.