mail-compose.js no longer has its own Contacts suggestion code. Its To, Cc and Bcc lines use public/assets/address-suggest.js, as Invoicing's Send panel does; each field names the address its typed word is appended to, so Mail keeps /mail/contacts/suggest and its access check. In Mail, Escape in a suggestion list now closes only the list.
Internal: one Contacts suggestion script for Mail and Invoicing
Mail's compose panel now uses address-suggest.js, the script Invoicing's Send panel uses, instead of its own copy.