Unable to Send Mass Volumes of Email

The 1,000 emails per day threshold does not apply to Butler shared mailboxes or any messages sent via third-party apps or services.

Errors Seen if Threshold is Met

If you are receiving any of the following error messages, it is possible you may have hit the set email threshold of 1,000 emails allowed per day. 

• "Unable to send email, blocked by Microsoft."
• "Unable to send emails to third-party groups."
• "Delivery has failed because you are not a valid sender."
• "Your message couldn't be delivered because you weren't recognized as a valid sender. The most common reason for this is that your email address is suspected of sending spam and it's no longer allowed to send messages outside of your organization. Contact your email admin for assistance."

Risks of Not Having an Email Threshold

Without any limits on how many emails can be sent per hour, our email system and all Butler users can be exposed to significant risks.

1. Email Account Compromise
   • If a bad actor gains access to a Butler email account, they can quickly send out thousands of emails in a short period. Without a threshold, this can overwhelm the mail system, spread phishing attacks quickly, or cause data loss.
2. Butler Emails Being Put on a "Do Not Trust" List
   • When large volumes of suspicious or unsolicited emails are sent, external email providers (like Gmail, Outlook, etc.) may detect and begin blocking our messages. This would apply to all emails from a butler.edu address, meaning future emails - including legitimate ones - may go to recipients' spam folders or be rejected entirely.
3. Accidental Email Flooding
   • Mistakes happen. Without a limit, a misconfigured script or automation could unintentionally send thousands of emails at once. This can cause confusion and reputational harm. 

Why an Email Threshold Helps

Setting a sending threshold is a proactive security measure that provides:

1. Protection Against Abuse
   1. Limits help detect and stop abnormal activity, especially if an account has been compromised.
2. Reputation Safeguarding
   1. Email providers trust domains that send mail in reasonable volumes. Staying under a set threshold keeps our email system's "sender reputation" healthy and reduces the chance of emails from butler.edu addresses being flagged as spam.
3. Early Threat Detection
   1. If someone tries to send more than 1,000 emails in 24 hours, the system will flag it. This allows IT staff to investigate quickly and stop spam or malicious activity before it spreads.

Remember: These limits are not restrictions - they're protections. By staying within them, we help ensure a safer, more reliable email security system for everyone. 

What if I need to send more than 1,000 emails?

We understand that some users have legitimate needs for high-volume communication (e.g., newsletters or event announcements). If this applies to you, please submit a case for Information Technology at ask.butler.edu.