Enhancement: fetch mails in bulk (#5249)

Co-authored-by: Trenton H <797416+stumpylog@users.noreply.github.com>

src/paperless_mail/mail.py

@@ -569,6 +569,7 @@ class MailAccountHandler(LoggingMixin):
                 criteria=criterias,
                 mark_seen=False,
                 charset=rule.account.character_set,
+                bulk=True,
             )
         except Exception as err:
             raise MailError(