Why are recruitment emails to higher education institutions being marked as spam in Office 365?
Matthew Whittaker
Co-founder & CTO, Suped
Published 27 Jun 2025
Updated 17 Aug 2025
7 min read
Recruitment emails are vital for higher education institutions, but it's incredibly frustrating when those messages consistently end up in spam folders, especially within Office 365. I've encountered many clients facing this exact problem. They're sending messages, receiving 250 delivery responses, yet the emails aren't reaching the intended recipients, indicating they're likely being quarantined or marked as spam. This can significantly impact enrollment efforts and institutional outreach.
Office 365, with its robust spam filters, is notoriously difficult to penetrate if your sending practices aren't aligned with their strict requirements. Unlike general email marketing, recruitment emails to educational institutions often face unique challenges due to the specific configurations and heightened security measures employed by these networks. My goal is to shed light on why this is happening and offer actionable solutions to improve your email deliverability.
Understanding Office 365 spam filtering
Office 365's spam filtering mechanisms are dynamic and constantly evolving. They analyze a multitude of factors to determine whether an incoming email is legitimate or spam. This includes sender reputation, content analysis, and user feedback. When emails are sent in bulk, especially for recruitment, they can easily trigger these filters if not handled carefully.
A common scenario I've observed is messages being assigned a high Spam Confidence Level (SCL), such as SCL:9. When an email reaches this threshold, many Office 365 tenants are configured to automatically drop the mail, even if a 250 response indicates initial delivery. This often happens because enough recipients have marked similar emails as spam, or other underlying reputation issues exist. You can learn more about how Microsoft addresses spam issues.
Furthermore, educational institutions often employ additional layers of email security beyond standard Outlook or Office 365 settings. These can include third-party spam appliances, custom blocklists (or blacklists), and stricter content filtering rules tailored to protect students and staff from phishing and unwanted solicitations. This means a blanket approach to deliverability might not work.
Common reasons for recruitment emails being flagged
Several factors commonly contribute to recruitment emails being flagged as spam by Office 365, especially when targeting higher education. These often boil down to how your emails are perceived, both technically and contextually.
Sender reputation: If your domain or IP address has a history of sending emails that recipients mark as spam, or if it's listed on a public or private blacklist or blocklist, Office 365 will be highly suspicious. This is a critical factor for any sender, but particularly for those sending bulk messages.
Content and personalization: Generic, templated messages lacking personalization are often flagged. Spam filters look for characteristics like excessive links, suspicious keywords, or poorly formatted HTML. Higher education recipients expect relevant and tailored communications, making generic content a red flag.
Recipient engagement: Low engagement (few opens, clicks) combined with high complaint rates directly signals to Office 365 that your emails are unwanted. Institutions often have very active users who quickly report unwanted mail.
List quality: Sending to outdated, unverified, or purchased lists is a deliverability killer. These lists often contain spam traps or inactive addresses, which severely damage your sender reputation. A high bounce rate or engagement with spam traps will quickly land your emails in the junk folder.
In the context of higher education, there's a delicate balance between reaching a broad audience and maintaining deliverability. Many colleges and universities use third-party vendors for mass email communications. If these systems aren't correctly configured, they can easily trigger spam filters. This is why it is so important to adhere to new sender requirements, such as those that major email providers have recently put in place.
My recommendation here is to regularly check your email domain reputation. A poor reputation score will severely hamper your efforts to reach the inbox. It's often the root cause of issues where emails are seemingly delivered but never seen.
Technical factors and authentication
Even with perfect content and a great list, technical misconfigurations can cause your emails to go to spam. Email authentication protocols are crucial for verifying your sender identity and proving your emails are legitimate.
SPF (Sender Policy Framework): This record specifies which mail servers are authorized to send emails on behalf of your domain. An incorrect or missing SPF record can lead to emails failing authentication and being marked as suspicious.
DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your emails, allowing the recipient's server to verify that the email hasn't been tampered with in transit. Failing DKIM can also signal a problem.
DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC builds on SPF and DKIM, telling receiving servers what to do with emails that fail authentication. A DMARC policy set to p=reject or p=quarantine, while good for security, will lead to emails being blocked or junked if your SPF or DKIM alignment is off. You can check a simple guide to DMARC, SPF, and DKIM.
Misconfigured third-party ESPs: If you're using an email service provider (ESP) like Informz (as mentioned in the scenario) to send emails, it's crucial that they are properly authorized in your DNS records. Often, SPF records are not correctly updated to include the ESP's sending servers, which can cause authentication failures and result in emails landing in Office 365 spam folders.
Example SPF record setup
A common mistake is forgetting to include your ESP's SPF record. If your recruitment emails are sent via a third-party, their mail servers must be authorized.
Without the correct include statements for all your sending services, Office 365 will deem your emails unauthorized and likely quarantine them.
Best practices for higher education recruitment emails
To improve deliverability for your recruitment emails, especially into Office 365 environments, I recommend a multi-faceted approach focusing on both technical setup and content strategy.
Proactive measures
Verify authentication records: Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned with all your sending sources, including any third-party ESPs. Check for common DMARC issues in Microsoft 365.
Segment your lists: Separate your recruitment emails from other general communications. This allows for more targeted content and better tracking of engagement metrics specific to this audience.
Monitor sender reputation: Use tools like Google Postmaster Tools for your domain to monitor spam rates, IP reputation, and domain reputation. This provides valuable insights into how email providers perceive your sending practices.
Content strategy
Personalization: Go beyond just using the recipient's name. Tailor the content to their specific interests, academic programs, or stage in the application process. Generic cold emails are more likely to be flagged.
Clear call to action: Make it obvious what you want the recipient to do next. Avoid vague language or too many options, which can appear suspicious to filters.
Avoid spam triggers: Minimize excessive capitalization, exclamation marks, suspicious phrases, or overly image-heavy emails. These are common characteristics of spam.
List hygiene and engagement
Maintain a clean list: Regularly remove inactive or bouncing email addresses. Implement a double opt-in process for new subscribers to ensure genuine interest and prevent spam traps.
Encourage engagement: Prompt recipients to add you to their safe sender list or address book. Encourage replies to foster two-way communication, which can boost your sender reputation.
Provide easy unsubscribe: A clear and functional unsubscribe link is not just a legal requirement, but it also helps prevent spam complaints. If recipients can't easily opt out, they're more likely to mark your email as spam.
Remember, email deliverability is an ongoing process. Consistent monitoring and adaptation to new challenges, like the evolving nature of Office 365's filters, are key to ensuring your recruitment messages reach their intended audience. If your emails are still landing in the Microsoft spam folder, consider a deeper dive into your email infrastructure and content strategy.
Views from the trenches
Best practices
Always maintain robust email authentication: SPF, DKIM, and DMARC are non-negotiable for deliverability.
Segment your audience precisely; highly targeted emails perform better and reduce spam complaints.
Monitor your sender reputation continuously to catch issues before they escalate.
Implement a feedback loop to quickly identify and address recipient complaints.
Regularly clean your email lists to remove inactive or problematic addresses.
Common pitfalls
Sending to unverified lists, leading to high bounce rates and spam trap hits.
Using generic, untargeted content that triggers spam filters and annoys recipients.
Neglecting to monitor sender reputation, allowing issues to fester unnoticed.
Ignoring bounce messages, which indicate fundamental problems with your email list.
Failing to update DNS records for all third-party sending services.
Expert tips
For Office 365, focus on user engagement: encourages recipients to interact and mark your emails as 'not spam'.
Be aware that higher education institutions often have stricter email security policies than standard organizations.
Personalize beyond just the name; tailor content to the specific stage of the recruitment journey.
If emails are not bouncing but also not being opened, it's a strong sign of quarantine or direct spam folder placement.
Consider engaging with recipients through multiple channels, not just email, to build trust and encourage positive email interaction.
Expert view
Expert from Email Geeks says that spam filters are always changing, and Office 365 is consistently one of the tougher filters to crack for email deliverability.
2024-09-02 - Email Geeks
Marketer view
Marketer from Email Geeks says they are receiving 250 responses indicating delivery, but messages are not reaching users, which suggests they are being quarantined or marked as spam.
2024-09-04 - Email Geeks
Ensuring your recruitment messages reach the inbox
Overcoming deliverability challenges with recruitment emails to higher education institutions in Office 365 environments requires a comprehensive strategy. It's not just about sending emails, it's about building and maintaining a trusted sender reputation.
By ensuring your technical setup is flawless, your content is highly relevant and personalized, and your mailing lists are meticulously maintained, you can significantly improve the chances of your vital recruitment messages landing in the inbox rather than the spam folder. Remember, higher education recipients and their IT departments prioritize security and relevancy, so align your practices accordingly to ensure your outreach efforts are successful.
Office 365. I've encountered many clients facing this exact problem. They're sending messages, receiving 250 delivery responses, yet the emails aren't reaching the intended recipients, indicating they're likely being quarantined or marked as spam. This can significantly impact enrollment efforts and institutional outreach.
Outlook or Office 365 settings. These can include third-party spam appliances, custom blocklists (or blacklists), and stricter content filtering rules tailored to protect students and staff from phishing and unwanted solicitations. This means a blanket approach to deliverability might not work.
