fix: Add validation for the inbox name to avoid special characters (#4920)

config/locales/en.yml

@@ -53,6 +53,8 @@ en:
         host_unreachable_error: Host unreachable, Please check the IMAP address, IMAP port and try again.
         connection_timed_out_error: Connection timed out for %{address}:%{port}
         connection_closed_error: Connection closed.
+      validations:
+        name: should not start or end with symbols, and it should not have < > / \ @ characters.
 
   reports:
     period: Reporting period %{since} to %{until}