EML
A single-message file in MIME format, containing headers, body, and attachments. EML files are widely supported across email clients and are useful for archiving or sharing individual messages.
EML is a plain-text file format defined by RFC 5322 that holds exactly one email message. The file begins with header fields — From, To, Subject, Date, and various technical headers — followed by a blank line and then the message body. If the message has attachments or an HTML version, those are encoded as MIME parts within the same file.
Because the format is an open standard, EML files open in most email clients on any operating system: Thunderbird, Apple Mail, Outlook, and many others can import or display them directly. This portability makes EML a practical choice for archiving individual messages or sharing them outside of a mail service.
When working with large collections of EML files, searching across all of them at once is the main challenge. Mbox Viewer can open individual EML files and apply the same full-text and metadata search capabilities it provides for MBOX archives, allowing you to locate messages by sender, date range, subject, or attachment name.
Related terms
A plain-text file format that stores multiple email messages concatenated together, each beginning with a "From " separator line. It is the format Google Takeout produces when you export your Gmail archive.
Microsoft Outlook's proprietary binary format for a single email message, storing headers, body, and attachments in a Compound Document Structure. Unlike EML, MSG is not a plain-text standard.
Multipurpose Internet Mail Extensions — the standard that defines how email messages encode non-ASCII text, HTML bodies, attachments, and other binary content within the plain-text structure of email.