Overview
To enhance the university’s email security and reduce the impact of compromised accounts, Purdue University is enforcing outbound email sending limits. As of March, 2026, student email accounts are subject to email sending limits. Beginning July 1, faculty, staff, and student workers’ accounts will also be subject to sending limits, with higher thresholds than those applied to student accounts.
These limits apply to Purdue campuses: PWL, PNW, PFW, & Purdue Indianapolis.
Users who exceed the limits may receive a Microsoft Outlook non-delivery report (NDR) containing an error similar to: ‘550 5.1.8 Access denied, bad outbound sender’
Once blocked, the account will be unable to send email until Purdue IT is contacted, the activity is reviewed, and the restriction is removed.
Sending Limits
Student email accounts are limited to:
- Maximum of 200 emails per hour, OR
- Maximum of 500 emails per day
Faculty & Staff & Students Workers email accounts limited to:
- Maximum of 500 emails per hour, OR
- Maximum of 1000 emails per day
(Whichever limit is reached first will trigger restriction.)
Important: Limits are based on the number of recipients, not the number of messages only. For example, a single email sent to 100 recipients counts as 100 recipients toward the limit. Emails sent to a Distribution Group or Listserv address count as a single recipient.
Example: If a student sends an email to 198 recipients at 1:15 PM and then sends additional messages to two or more recipients before 2:15 PM, the account may exceed the hourly limit and be blocked. However, if students wait until after 2:15, then send those additional emails, the account will not be blocked due to the hourly limit, but still recipients continue to accumulate toward the other enforced daily limit of 500 (resets 12 midnight).
What Happens if My Account Is Blocked?
If your account exceeds the sending limits, you will be blocked from sending email. You will still be able to receive and read messages, but you will not be able to send new messages or reply to existing emails until the restriction is removed.
How to Restore the Ability to Send Messages
If your account is blocked due to exceeding the email sending limits, you must contact Purdue IT Support (create a support request ticket or call the service desk). Purdue IT will perform a security review to verify the activity was legitimate and that the account has not been compromised. If approved, the sending restriction will be removed.
Sending capability is typically restored within 15 minutes, although Microsoft synchronization delays may occasionally require 1-24 hours. Once restored, the account will remain subject to the same sending limits.
Why This Change Was Implemented
This policy helps to:
- Protect accounts being compromised or misused.
- Reduce the spread of spam and phishing emails
- Improve the university’s overall email security posture
This change also aligns with Purdue University’s official Email Policy outlined here:
https://www.purdue.edu/vpec/policies/information-technology/s7/
Need to Send to Larger Audiences?
- Before sending large-volume emails, review the communication options listed in the mass emailing options section below. These tools are designed for communicating with larger audiences and may be more appropriate than sending emails directly to individual recipients.
- If your business or academic need cannot be met using those options, you may request a temporary or permanent sending-limit exception by submitting the exception request form: https://forms.office.com/r/2a4pvsGFT7
Additional Notes
- Student club moderators are encouraged to use their club’s dedicated email account for communications, as these accounts currently are not subject to the same sending limits.
- Departments' shared mailboxes are currently not subject to the same limits.
Mass Emailing Available Options
- Qualtrics
Use Qualtrics for surveys, polls, event registrations, sign-ups, and feedback collection.
https://service.purdue.edu/TDClient/32/Purdue/KB/Article/81/Why-can-t-I-login-to-Qualtrics
- Brightspace
For instructor-to-student and course-related communications, instructors and TAs should use Brightspace as the primary communication platform. Course announcements, updates, and class communications are expected to be distributed through Brightspace whenever possible rather than through direct mass email.
Summary: Which Option Should I Use?
- Small-scale communications within sending limits → Regular Email.
- Ongoing communications to a larger number of Purdue recipients (Only Internal Purdue Users, with Limited Approval-Based Exceptions) → Microsoft 365 or Distribution Groups.
- Course announcements and student communications → Brightspace.
- Send announcements and newsletters to defined Purdue or External subscriber-based communications → Listserv
- Collecting responses (events, surveys, feedback) → Qualtrics
- Need to send large, official communications directly through Outlook that exceed the Purdue sending limits described in this KB, but remain within the maximum sending limits supported by Microsoft Exchange Online. → Request a sending-limit exception
Still Not Sure?
If you are unsure which solution best fits your needs, contact Purdue IT Support before sending large or repeated email campaigns.