Microsoft outlook.com generates a Message-ID as the below:

```
Message-ID:
 <XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX@YYYYYYYYYYYYY.ZZZZZZZZ.prod.outlook.com>
```

This results splitting Mailman log into multiple lines as the below:

```
[2024-04-16 16:00:13 +0900] [3640656] HOLD: listname@example.com post from poster@example.com held, message-id=
 <XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX@YYYYYYYYYYYYY.ZZZZZZZZ.prod.outlook.com>: Emergency moderation is in effect for this list
```

Closes #1139