Recruitment emails to higher education institutions are frequently marked as spam in Office 365 due to a multifaceted interplay of factors, including the adaptive and stringent nature of Office 365's spam filters, the sender's IP address and domain reputation, email content and engagement metrics, and the proper configuration of email authentication protocols. A poor IP reputation stemming from prior spam activity or blocklisting significantly increases the likelihood of emails being flagged. Additionally, low engagement rates (opens, clicks), high bounce rates, and spam complaints negatively impact sender reputation. Generic or unsolicited content also contributes to deliverability issues. Proper sender authentication using SPF, DKIM, and DMARC is crucial for verifying sender identity and preventing spoofing. Maintaining list hygiene by removing inactive subscribers and gradually warming up IP addresses are essential for establishing a positive sender reputation. Office 365 leverages Spam Confidence Levels (SCL), with high SCL scores potentially leading to emails being dropped or filtered.
9 marketer opinions
Recruitment emails to higher education institutions are often marked as spam in Office 365 due to a combination of factors related to sender reputation, email content, and technical configurations. Poor sender reputation stems from low engagement rates (opens, clicks), high bounce rates, spam complaints, or being listed on blocklists. Content that is perceived as unsolicited or generic also contributes to emails being flagged as spam. Additionally, not properly configuring email authentication protocols (SPF, DKIM, DMARC) can hinder deliverability. Strategies to improve deliverability include maintaining good list hygiene, using a dedicated IP address, warming up the IP address gradually, personalizing email content, and optimizing send times.
Marketer view
Email marketer from GMass details that warming up your IP address gradually before sending high volumes of emails helps to establish a positive sender reputation. This involves slowly increasing the sending volume over time and engaging with recipients to demonstrate legitimacy.
7 Jul 2023 - GMass
Marketer view
Email marketer from Reddit suggests that recruitment emails often get flagged as spam due to the content being perceived as unsolicited and generic. Personalizing emails and tailoring them to specific recipients can help improve engagement and avoid spam filters.
2 Feb 2022 - Reddit
4 expert opinions
Recruitment emails to higher education institutions are often marked as spam in Office 365 due to adaptive and tough spam filters. A key factor is the sender's IP address reputation. A poor IP reputation stemming from previous spam activity can lead to emails being marked as spam. Furthermore, if recipients mark the email as spam, it can receive a Spam Confidence Level (SCL) of 9, causing Office 365 to drop the mail. Proper sender authentication (SPF, DKIM, DMARC) is also crucial for improving deliverability and verifying sender identity.
Expert view
Expert from Spam Resource (Laura Atkins) explains that IP address reputation is essential. If the IP address used to send recruitment emails has a poor reputation due to previous spam activity or being on blocklists, Office 365 is more likely to mark those emails as spam.
4 May 2023 - Spam Resource
Expert view
Expert from Email Geeks says that Spam filters are adaptive and always changing and O365 is one of the tougher filters.
2 Dec 2021 - Email Geeks
4 technical articles
Recruitment emails to higher education institutions can be marked as spam in Office 365 due to several technical and policy-related factors. Microsoft advises following best practices for bulk email, including authenticating emails with SPF, DKIM, and DMARC, maintaining a good IP address reputation, and providing an easy way to unsubscribe. Exchange Online uses Spam Confidence Levels (SCL) to assess the likelihood of a message being spam, with high SCLs leading to filtering or rejection, influenced by content, sender reputation, and user complaints. DMARC, SPF protocols help email receivers verify that emails are authorized, preventing phishing and improving deliverability.
Technical article
Documentation from Microsoft Learn explains that if you are sending bulk email, Microsoft advises following best practices for deliverability. This includes authenticating your email with SPF, DKIM, and DMARC; ensuring your sending IP addresses have good reputations; and providing an easy way for recipients to unsubscribe.
6 Mar 2025 - Microsoft Learn
Technical article
Documentation from RFC details technical specifications for Sender Policy Framework (SPF), explaining it allows domain owners to specify which mail servers are authorized to send email on behalf of their domain. Receivers can then verify the SPF record and reject unauthorized emails, mitigating spoofing and improving deliverability.
17 Apr 2025 - RFC
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