Mail, IMCEAEX error

For the senders

If sending mail from

youraddress@tue.nl
to a
recipient@win.tue.nl

suddenly does not work but triggers a delivery report including lines such as:

Generating server: XSERVER22A.campus.tue.nl

IMCEAEX- O=TUE OU=TUE+20Campus cn=Recipients cn=account@tue.nl

#550 5.1.1 RESOLVER.ADR.ExRecipNotFound; not found ##

then follow these instructions or the these in more detail , deleting all of the matches for the concerned recipient.

For the recipient

And if you are the intended recipient@win.tue.nl:

Point the exchange users, all your

contacts@tue.nl

to this page. They all potentially have entries in their automatic completion caches that no longer work.

Unfortunately, this is a problem on the mailclients, the computers of the senders, not on the sending mailserver of @tue.nl and not on the receiving mailserver of @wintue.nl.

So there is no way for system administrators to solve the problem on the servers.

For both:

We found that sending mail from other origins than those@tue.nl to the concerned recipient@win.tue.nl still works, so the problem is on the sending side.

In more detail:

If

You, as sender of mail to recipient@win.tue.nl
  • using one of:
    • Outlook
    • Outlook Web Access, visiting https://webmail.tue.nl using Explorer
  • from inside the TUE campus, the tue.nl subnet
    (or from a VPN connection to that subnet)
  • in the past
    have entered the recipient@win.tue.nl using the automatic completion cache, that is:
    • Type a few starting letters for the address
    • One or more matches appear
    • the desired recipient address was clicked
  • now
    • send another mail to the same recipient@win.tue.nl,
      applying that automatic completion cache again
    • suddenly get a delivery error message including:
      IMCEAEX- O=TUE OU=TUE+20Campus cn=Recipients cn=account@tue.nl
      where this account is a valid account name of the intended recipient

then

Remove the entries for the recipient from your automatic completion cache, as follows:
  1. Type again a few starting letters for the recipient in the To: field, until one or more matches appear.
  2. Select but do not click a match
    for the concerned recipient.
  3. Now delete the selected entry by typing the Delete key.
    On Outlook 2010, you can also click the delete option that should appear on the entries.
  4. Repeat this procedure for all of the matching entries for the concerned recipient.

    This is needed because you cannot see which of them are invalid and will cause the error again.

Now

You should be able to send mail to the concerned recipient by re-entering the address:
  • selecting from the address book
  • typing manually
That address will appear next time in your automatic completion cache and the new entry will work.

Possible causes

The mail delivery problem is a result of some course of history, which we still do not understand. We think that changes in the Exchange environment play a role:

  • The mail contacts for many recipients@win.tue.nl were removed in July 2016, after we found that they were not needed to relay mail to these recipients and many of the addresses were outdated.
  • In the past, we had custom recipients to relay mail to recipient@win.tue.nl. When they were removed or replaced by an mailbox account, the delivery problem sometimes also occured.
  • A change of Exchange versions

See also


Contact us | Webmaster

Questions? Mail to helpdesk.win@tue.nl