Junk mail
Junk mail is a colloquial term for unsolicited or unwanted email messages that recipients did not ask for and do not wish to receive, used broadly as a synonym for spam. In most email clients, the junk folder or spam folder is where email filters automatically route messages they believe are unwanted. When a recipient clicks ‘Mark as junk’ or ‘Report spam’ in their email client, it registers a complaint against the sender’s IP and domain with the inbox provider, which affects that sender’s future deliverability.
Junk mail filtering is performed by algorithms that evaluate a combination of factors: the sender’s reputation, the authentication status of the email, the content and formatting of the message, and the engagement behaviour of the specific recipient and similar recipients. An email that looks like marketing material to the algorithm, regardless of whether the recipient actually wants it, may be routed to the junk folder even if it is entirely legitimate. This is why sender reputation and list engagement are so important.
For B2B email marketers, avoiding the junk folder requires maintaining a positive sending reputation through good list hygiene and consistent authentication. It also requires earning genuine engagement through relevant content, since inbox providers increasingly use engagement signals as a factor in filtering decisions. The best protection against the junk folder is an audience that genuinely wants your emails and a programme that gives them good reasons to open, click, and engage every time you send.
What is the difference between junk mail and spam?
The terms are used interchangeably in most contexts. Spam has become the dominant term in digital marketing and technology; junk mail is more commonly used in Outlook’s interface and in casual conversation. Both refer to unsolicited or unwanted email messages. In a strictly technical sense, spam often refers to bulk unsolicited commercial email, while junk mail is a broader term that can include any unwanted correspondence, but in practice the distinction rarely matters for email marketing purposes.
How do email filters decide what goes to junk?
Email junk filtering is a multi-factor process. Filters evaluate the sender’s IP and domain reputation, the authentication status of the message (whether SPF, DKIM, and DMARC pass), the content of the email (certain words, formatting patterns, and HTML structures are associated with spam), the recipient’s own behaviour with this sender, and in aggregate systems like Gmail, the behaviour of many recipients with similar messages. No single factor determines junk routing; it is the combined weight of all signals.
What should I do if my emails are going to the junk folder?
Start by diagnosing the cause. Check your IP and domain reputation using tools like MXToolbox and Google Postmaster Tools. Verify that your SPF, DKIM, and DMARC records are correctly configured. Review your bounce and complaint rates for recent campaigns. Examine your email content for spam trigger patterns. Check whether the issue affects specific inbox providers or all of them, as provider-specific issues point to reputation problems and universal issues point to authentication or content problems.