Regarding the ML (Mailman) provided by our Mail Hosting Service, an incident occurred in which unsubscription notification emails were erroneously sent. We deeply apologize for any concern and inconvenience this may have caused to all users. Please note that this incident has no impact on your mailing list registration information. Members have not actually been unsubscribed, so you may continue to use the service as usual.

1. Date and Time of Occurrence 
Sunday, August 23, 2026, around 20:21 – 22:05

2. Subject Lines of Erroneously Sent Emails 

• [ML Name] メーリングリスト: あなたのメールアドレスを退会しました
• [ML Name] メーリングリスト: 退会通知

3. Cause 
When deleting test data migrated to the verification environment during system update work for the Mail Hosting Service, unsubscription notification emails were automatically sent in conjunction with the deletion process.

4. Impact and Current Status 
There is no impact (unsubscription processing) on members of the mailing lists currently in use.

5. About System Update

Details of the update are published on the following information site. All users are requested to check this page.
https://sites.google.com/kyoto-u.ac.jp/mhs2026update/