How is the requester's profile name defined when a ticket is created from a new user via email?
It depends on how the email is sent by the user's email account. If the header in the source contains the Reply-To header field, then we'll get the name from that field:
Priscila Zendeskian <email@example.com>
Zendesk would set the user's name to "Priscila Zendeskian".
However if the header just shows Reply-To
: <firstname.lastname@example.org>, Zendesk would set as just the email prefix, "priscilazen".
In cases where Reply-To: field is not available, the system will look for the From: field.
See view the original email for more information on how to view the source header information in a ticket.