try to work around mailparser not decoding rfc2047 displaynames

this pulls in changes in our fork of rust-email  to also correctly
generate rfc2047 encoding

src/mimefactory.rs

@@ -1051,3 +1051,40 @@ pub fn needs_encoding(to_check: impl AsRef<str>) -> bool {
         !c.is_ascii_alphanumeric() && c != '-' && c != '_' && c != '.' && c != '~' && c != '%'
     })
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use email::rfc2047::decode_rfc2047;
+    use mailparse::{addrparse, MailAddr};
+
+    #[test]
+    fn test_render_email_address() {
+        let display_name = "ä space";
+        let addr = "x@y.org";
+
+        assert!(!display_name.is_ascii());
+
+        let s = format!(
+            "{}",
+            Address::new_mailbox_with_name(display_name.to_string(), addr.to_string())
+        );
+
+        println!("{}", s);
+        assert!(s.is_ascii());
+
+        assert_eq!(s, "=?utf-8?q?=C3=A4_space?= <x@y.org>");
+
+        match &addrparse(&s).unwrap()[0] {
+            MailAddr::Single(info) => {
+                // XXX addrparse should not return rfc2047 encoding
+                // but the decoded string, see
+                // https://github.com/staktrace/mailparse/issues/50
+                let s = decode_rfc2047(&info.display_name.clone().unwrap());
+                assert_eq!(s, Some(display_name.to_string()));
+                assert_eq!(info.addr, addr.to_string());
+            }
+            _ => panic!(),
+        }
+    }
+}