[tz] Charset for Digest Emails

[Owen Leibman]

I have been subscribed to the “tz digest”, which comes out about once a day. Whenever a non-ASCII character is part of the message, it is rendered as multiple question marks. This seems to be because the message is sent with a header:
Content-Type: text/plain; charset="us-ascii"
This is only a minor nuisance. However, as an experiment, I changed my subscription to receive the messages directly rather than in digest form. A message today used an emoji outside the ASCII range, and it was rendered exactly as intended. It came with the following header:
Content-Type: text/plain; charset="UTF-8"; format=flowed
Is there a setting that could/should be changed so that the digest is sent with the same header?
This email and any files transmitted with it are confidential, proprietary and intended solely for the individual or entity to whom they are addressed. If you have received this email in error please delete it immediately.