Why are test emails with TEST in the subject line going to the spam folder in Outlook?

Email marketer from Mailjet shares that using words like 'test' in your subject line can trigger spam filters. It’s best to use real subject lines even for test emails to avoid being flagged as spam.

Email marketer from Campaign Monitor responds that subject lines that include the word test are flagged by Outlook as spam because spammers send out test emails frequently.

Email marketer from Email Marketing Forum responds that the word 'test' is a very common trigger for spam filters. Outlook is probably just identifying this now and filtering to junk folder.

Email marketer from EmailOctopus Blog shares that certain words are more likely to trigger spam filters, with 'test' being a common example. Repeated use of such terms, especially in the subject line, can lead to emails being marked as spam.

Email marketer from Sender.net responds that subject lines like "test" or "testing" are considered spam triggers and can cause your emails to land in the junk folder.

Email marketer from Email Geeks responds by stating that if emails with 'TEST' in the subject are now going to the spam folder only at Outlook, and the same email without 'TEST' is not, then there was a change at Outlook in how they are handling the email with 'TEST' in the subject, and the sender should stop putting 'TEST' in the subject.

Email marketer from GMass shares that subject lines containing the word 'test' are red flags for spam filters. Avoid such terms and use a relevant, engaging subject line instead.

Email marketer from Reddit shares that using 'Test' in the subject line can trigger spam filters due to its common use in spam emails. It's advisable to use a more descriptive and realistic subject line even for tests.

Expert from Spamresource highlights that using 'Test' in the subject line is a common mistake that triggers spam filters. Due to spammers commonly using such terms, these emails are often flagged as unwanted or harmful.

Expert from Word to the Wise, Laura Atkins, explains that filters have learned over time to identify the word 'test' in the subject line as suspicious. Even if used legitimately for testing, the association with spam has caused these emails to be treated as such.

Expert from Email Geeks shares that spam filters are based on machine learning and are constantly learning and changing based on what is happening in their systems. What worked before won't always work today or in the future. Filter maintainers also don't announce changes.

Expert from Email Geeks explains that sending bulk mails with the subject line 'TEST' is an incredibly bad idea and something that, over time, will result in mail being bulked.

Documentation from Litmus explains that spam filters look for various factors, including suspicious subject lines. Using generic terms like 'Test' without meaningful content can significantly increase the likelihood of being flagged as spam.

Documentation from Microsoft Support explains that including 'Test' or 'Testing' in the subject line can be identified as unsolicited email by the Junk Email Filter, which will automatically send the messages to the Junk Email folder.

Documentation from Spamhaus explains that sending test emails with the word 'test' in the subject line can negatively affect your sender reputation because spammers often use similar tactics, so it's better to avoid these in the real world.