Why is Google marking its own emails as dangerous?

Google marking its own emails as dangerous stems from a variety of factors spanning from technical vulnerabilities and content analysis to user behavior and compromised accounts. Google's internal infrastructure, although trusted, is not immune to abuse, and emails originating from suspicious sources within the system are flagged. This includes compromised accounts sending spam or phishing attempts and Google calendar invite abuse leading to spam or malicious links. Google assesses email trustworthiness based on authentication (SPF, DKIM, DMARC), spam complaints, and sending practices. The algorithms that the emails pass through are constantly evolving with new patterns associated with malicious activity so what once was safe may trigger security warnings. Poor sending practices (even with proper authentication), domain and IP reputation issues, and content resembling phishing scams trigger filters. Third-party applications and integrations with access to Gmail accounts can also introduce vulnerabilities and result in emails being flagged. Even spoofed email addresses from illegitimate sources can be flagged as dangerous. Compromised accounts, reputation issues, DMARC bypass attempts, and poor quality content can contribute to deliverability issues.

Google marks its own emails as dangerous for various reasons, despite being the origin of the email. These reasons range from compromised accounts and the use of Google's infrastructure for abuse, to evolving spam filtering techniques and domain reputation issues. The content of the emails is also scrutinized for phishing attempts or suspicious links, and poor sending practices, even with proper authentication, can lead to emails being flagged. Third-party app integrations can also contribute to the problem if they violate Google's policies.

Google may mark its own emails as dangerous due to a few key reasons. These include instances where the content isn't genuinely Google-generated, especially concerning abuses via Google Calendar invitations, potentially forged emails bypassing DMARC, or simple calendar spam. Furthermore, reputation issues stemming from compromised accounts within Google's domains sending spam can trigger filters. Additionally, if Google's own systems and infrastructure were to be compromised, they would also flag their own emails as dangerous.

Google's own documentation reveals several reasons why its emails might be flagged as dangerous. These include emails originating from suspicious sources within Google's infrastructure, often due to compromised accounts sending spam or phishing attempts. Calendar invites can be abused to distribute spam and malicious links. Google uses various factors, like authentication, spam complaints, and sending practices, to assess email trustworthiness. Even with proper authentication, poor sending practices or high complaint rates can result in emails being flagged. Gmail's spam filters also target phishing scams, which can spoof legitimate email addresses, even Google's own.