Hi @Tammy Wong ,
I just observed that "name (name@keyman .com)" will display the whole thing "name (name@keyman .com)" in the recipient field
According to your description, this issue only happens to some specific users, do these users have any similarities (such as all your contacts or others)?
I did lots of tests on my Outlook 2016 for your issue, and according to my tests, when I add a member to my contact manually, the auto-complete list could show the "name (name@keyman .com)" and it also could display in the recipient field like below. Except this way, I haven't found other way to achieve the same effect.
Besides, if the recipient is just a member in your organization and not your contact, it would show the name <name@keyman .com> in autocomplete list and only show name in recipient field, which matches your description.
If this is not your case, please give me more information about your issue and I would give you more targeted help.
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