Why did Gmail mark an internal email as potentially dangerous?

Email marketer from Quora shares that this usually happens if the email content closely matches phishing attempts, includes unusual URLs or attachments, or contains suspicious language.

Email marketer from Mailjet FAQ states that emails with unusually high image-to-text ratios or mismatched character sets can trigger spam filters.

Email marketer from Email Marketing Forum suggests that if multiple recipients within your organization mark similar emails as spam, Gmail learns to flag those emails automatically.

Marketer from Email Geeks shares to have IT search the mail audit log to see why Google Workspace flagged it. It may be a false positive or something actionable.

Marketer from Email Geeks explains that these alerts are driven by ML models that produce “maybe” results, and feedback is used to help train the model. It may not be possible to pinpoint one specific cause.

Marketer from Email Geeks shares that if it sounds like other stuff Gmail thinks is spam, it may get flagged as suspicious.

Email marketer from Gmass explains that consistently sending emails with low engagement (opens, clicks) can negatively impact your sender reputation and lead to Gmail flagging your emails.

Email marketer from Super User shares that the use of URL shorteners can sometimes flag emails as suspicious if the destination is untrustworthy or the service is overused by spammers.

Email marketer from StackExchange explains that an email might be flagged if it originates from a newly created or rarely used IP address, as it could indicate a spammer.

Email marketer from Reddit suggests checking the email headers for authentication failures (SPF, DKIM, DMARC). If authentication fails, Gmail is more likely to flag the message.

Email marketer from Web Applications Stack Exchange explains that a sudden increase in email volume or velocity can be interpreted as spamming behavior by Gmail's filters.

Email marketer from Google Support Community explains that Gmail might flag a message as dangerous if it detects suspicious links or attachments, or if the sender's account has been compromised.

Expert from Spam Resource shares that if internal emails contain content similar to known spam patterns (e.g., certain phrases, excessive use of exclamation points, or unusual formatting), Gmail's content filters might mistakenly flag them.

Expert from Word to the Wise explains that internal emails can be flagged due to misconfigured authentication (SPF, DKIM, DMARC) even within the same domain. Ensure internal systems are properly configured.

Expert from Email Geeks responds that it's likely not a spam filter issue but Gmail may have flagged it as concerning.

Documentation from RFC Standard details that improper formatting of email headers can cause the algorithms of Google to misinterpret an e-mail as dangerous.

Documentation from DMARC.org explains that a properly implemented DMARC policy can help improve deliverability and reduce the likelihood of Gmail flagging legitimate emails.

Documentation from BIMI Group explains that implementing BIMI (Brand Indicators for Message Identification) can help establish brand trust and reduce the chance of Gmail flagging emails.

Documentation from Google Workspace Admin Help explains that Gmail uses machine learning to identify spam and phishing attempts. Factors include sender reputation, email content, and user reports.

Documentation from Google Security Blog indicates that Gmail's algorithms constantly evolve to detect new phishing tactics and malware distribution methods, which can lead to some internal emails being misclassified.