Scenario:
- You have Distribution Lists in your Exchange environment with external addresses as members.
- Therefore those external addresses exist as Contact Records in the Global Address List.
- Your company decides to hide those contact records (attribute: MSExchHideFromAddressLists= True)

Issue:
A blackberry user receives an email from an external person whose internet email address is one of these hidden contract records. The result is that a reply from the Blackberry to that address is an immediate delivery failure:

"(FYDIBOHF23SPDLT)/CN=RECIPIENTS/CN=stu_bee93@msn.85A51D19-0D2F-450B-BCAC-21E1E0BA2D51dADCBAE0'
The format of the e-mail address isn't correct. A correct address looks like this: . Please check the recipient's e-mail address and try to resend the message."

Unhide the contact record and the email is able to be replied to on the Blackberry.
Issue does not occur from Outlook Client or Owa. Issue also does not occur on new emails on the BB to that external address..only replies.

Any thoughts?

dont hide it

^ This.

In large corporate environments a tech does not always have the say on overall account policy.
Ignoring the replies, I'll just assume from that no-one has experienced this issue with hidden external accounts. Which may point to a co-existance mailrouting issue that I will therefore investigate.