Problem with the size of the To field in CRM Email form

Hi everyone

we use CRM 2016 SP1 on-premise. We are experiencing an issue with the size of the To field of the built-in email form whereby the field only displays up to three lines of email addresses and truncates the rest. Even when I resize the window, only three lines are visible not more. This is affecting our users' ability to check all email addresses in order to delete unwanted ones.

Is there any way to get the To field to expand/scroll so that users can see all email addresses?

Any help is greatly appreciated.