Do you want to message them all in one message? You can use Discourse Dynamic Groups to create a group with only users with TL2 and allow at least admins to send messages to that group.
Is this a one way announcement you want to send? Will there be more of them? If so then a group with a secure category might be more suitable, or a group you are allowed to @ mention.
If it’s a one off message, you can use bcc to the group you create. Each member will get their own message.
Thanks, Moin – I didn’t want to export & use external email per that linked topic, but I had not come across the Dynamic Groups plugin – looks that would do it!