To do an effective global search for an email address, you should enter the complete email address, in the format <user name>@<domain>.
If you use this format, global search treats this entry as a single keyword and returns anyone with that exact, complete email address.
This treatment of a recognized email address overrides the normal global search treatment of the . (period) and @ (at) characters as spaces.
If you enter a complete email address, such as email@example.com, global search returns that exact match only.
If you enter only firstname.lastname@example.org, global search treats it as a complete email address and only returns that exact match.
If you enter only john.brown, global search looks for two different keywords, john, and brown, and returns any records containing these two keywords.
The starts-with matching generally used by default in global search is not supported for email addresses because the complete email address is required for global search to interpret a keyword as an email address.