{"id":2111,"date":"2026-11-10T12:25:57","date_gmt":"2026-11-10T11:25:57","guid":{"rendered":"https:\/\/www.mailfino.com\/?p=2111"},"modified":"2026-11-10T13:53:57","modified_gmt":"2026-11-10T12:53:57","slug":"glossar-spam-filter","status":"publish","type":"post","link":"https:\/\/www.mailfino.com\/en\/glossar-spam-filter\/","title":{"rendered":"What is a spam filter?"},"content":{"rendered":"

A spam filter evaluates incoming email for unwanted or suspicious content. Email providers, company gateways, and email clients can filter at different points, using their own rules and signals.<\/p>\n\n\n\n

\"A<\/figure>\n\n\n\n

What signals can filters consider?<\/h2>\n\n\n\n

Filters may consider the sending IP address or domain, authentication, message content, links, and known signs of abuse. A blocklist or allowlist can affect the assessment. Which signals count and how much weight they receive depends on the service.<\/p>\n\n\n\n

What happens to a flagged message?<\/h2>\n\n\n\n

A receiving server can reject a message during transfer. If the service accepts it, it can label it, quarantine it, or place it in the spam folder. Legitimate messages can also be misclassified.<\/p>\n\n\n\n

Example of an authenticated email<\/h2>\n\n\n\n

A newsletter passes authentication but links to a domain the provider considers suspicious. The provider can still place the newsletter in spam. In a case like this, first check whether the server accepted or rejected the message, then investigate the link and other signals.<\/p>\n\n\n\n

Further reading<\/h2>\n\n\n\n