Outlook Email Address's wrapped in quotes

Hi,

I have a client who is running Office home and business 2016

When using outlook he is finding some of the email address he searches for are wrapped in quotes and some aren't. These address's can be for the same person mailto:john@john.com or "john@john.com".

What the frustrating bit is when he searches through outlook for John the search results are inconsistent due the duplication and the search does not group both email address's together.

I have unchecked the Straight quotes with smart quotes option in Autocorrect.

Has anyone experienced this type of issue before