While using an iOS device, you are receiving new emails in the 'Firstname-Lastname' format:
There is a need to change the Display format to 'Lastname-Firstname.' This article provides instructions on how to change the iOS device Display format.
Open the iOS Settings and scroll down to the Contacts section.
In the Contacts section, tap the Display Order option and choose Last, First option (or vice-versa).
The Contact details are displayed in the necessary order (i.e., Lastname, Firstname).