{"id":55,"date":"2010-12-27T19:52:31","date_gmt":"2010-12-27T19:52:31","guid":{"rendered":"http:\/\/greatmail.com\/blog\/?p=55"},"modified":"2025-10-21T03:16:47","modified_gmt":"2025-10-21T03:16:47","slug":"sender-authentication-with-dkim-and-spf","status":"publish","type":"post","link":"https:\/\/www.greatmail.com\/blog\/email-hosting\/sender-authentication-with-dkim-and-spf\/","title":{"rendered":"Sender Authentication with DKIM and SPF"},"content":{"rendered":"

Sender authentication technologies like DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) not only help control spam but also\u00a0improve deliverability of legitimate messages. Consequently,\u00a0these systems are\u00a0of interest to both email administrators and email marketers.<\/p>\n

What is sender authentication? In the most general sense, sender authentication measures the validity of a message source, and\u00a0this information\u00a0is used by\u00a0recipient servers to improve filtering and handling. Passing results should indicate the message\u00a0is of reputable origin; negative results may\u00a0mean further scrutiny through spam filtering or message blocking.<\/p>\n

Both SPF and DKIM attempt to validate the authenticity of a message sender by looking at the sending domain and qualifying that the server sending the message is legitimate.\u00a0 However, SPF and DKIM each approach this task differently and\u00a0have their own unique methodologies and\u00a0implementations.<\/p>\n

The primary objective of SPF is to control forged email<\/a>. SPF is a relatively simple system that utilizes text entries in the domain’s DNS allowing domain owners to specify what servers are permitted to send mail on behalf of\u00a0a particular\u00a0domain.\u00a0 SPF depends on the recipient server utilizing SPF lookups to validate that messages are authentic. Most server side spam filters like SpamAssassin<\/a>\u00a0perform\u00a0SPF lookups when filtering incoming mail.<\/p>\n

DKIM, on the other hand, “lets an organization take responsibility for a message while it is in transit,” as\u00a0stated on the DKIM.org<\/a> website. Compared to SPF, DKIM is a more advanced system utilizing cryptographic authentication\u00a0to verify a signature assigned to\u00a0a message on the sender’s server.\u00a0 DKIM requires configuration support on the SMTP server in addition to DNS entries that must be made on the sender’s domain.<\/p>\n

Unlike Sender Policy Framework (SPF) which authenticates\u00a0a message at the envelope level using the Return-Path header, DKIM validates a message using the From header.\u00a0 Because spammers commonly forge both of these headers, utilizing SPF and DKIM is good practice ensuring that a message originates from a valid server and is signed by an authorized handler for the domain.<\/p>\n

Setting up SPF simply requires adding a text entry to\u00a0your domain’s DNS.\u00a0 Most hosts or DNS providers can provide the necessary information to make this entry. In addition, there are several SPF wizards on the Internet and tutorials explaining SPF syntax. If you send from multiple servers, it is important to be sure to include all of these servers in your SPF entry.<\/p>\n

DKIM configuration is a bit more complicated than SPF and requires server side components to handle the DKIM signature.\u00a0 Most email hosting providers<\/a>\u00a0support DKIM\u00a0and can assist you with setting up DomainKeys for your domain and making the necessary text entries in\u00a0your DNS to enable DKIM signing.<\/p>\n","protected":false},"excerpt":{"rendered":"

Sender authentication technologies like DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) not only help control spam but also\u00a0improve deliverability of legitimate messages. Consequently,\u00a0these systems are\u00a0of interest to both email administrators and email marketers. What is sender authentication? In the most general sense, sender authentication measures the validity of a message source, and\u00a0this information\u00a0is … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,31,41],"tags":[44,46,47,45,48,21,22],"class_list":["post-55","post","type-post","status-publish","format-standard","hentry","category-email-hosting","category-email-marketing","category-spam-control","tag-dkim","tag-dkim-signing","tag-domainkeys","tag-domainkeys-identified-mail","tag-sender-authentication","tag-sender-policy-framework","tag-spf"],"yoast_head":"\nSender Authentication with DKIM and SPF - Greatmail Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.greatmail.com\/blog\/email-hosting\/sender-authentication-with-dkim-and-spf\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Sender Authentication with DKIM and SPF - Greatmail Blog\" \/>\n<meta property=\"og:description\" content=\"Sender authentication technologies like DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) not only help control spam but also\u00a0improve deliverability of legitimate messages. Consequently,\u00a0these systems are\u00a0of interest to both email administrators and email marketers. What is sender authentication? In the most general sense, sender authentication measures the validity of a message source, and\u00a0this information\u00a0is ... 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