Updates to Bulk Email Delivery
Microsoft has enforced a Recipient Rate Limit of 10,000 recipients per mailbox per day in Exchange Online. This limit affects the delivery of bulk emails to HKU staff and students and may cause bulk messages sent from individual accounts to be blocked.
To address this limitation and ensure reliable delivery, Information Technology Services (ITS) will introduce a new arrangement for sending bulk emails.
New Arrangement (effective 1 June 2026)
- Bulk emails will be sent from the address bulkemail@info.hku.hk to avoid delivery blocking.
- Emails will be sent “on behalf of” the submitting department name.
- Recipients may reply directly to the original sender.
Bulk emails will therefore appear in recipients’ mailboxes with the format:
Outlook Desktop App
Outlook Web App
