Prior to the availability of 8BITMIME implementations, mail user agents employed several techniques to cope with the seven-bit limitation, such as binary-to-text encodings (including ones provided by MIME) and UTF-7.
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SMTPUTF8 — Allow UTF-8 encoding in mailbox names and header fields, RFC 6531
Extended play | extended play | Extended Play | Extended Validation Certificate | Extended Copy Protection | Velvet Noise Extended | St Mihangel's, extended in 1988 by re-erecting St Enghenedl's Church, Llanynghenedl | San Diego State University's College of Extended Studies | List of wars extended by diplomatic irregularity | List of musical pieces which use extended techniques | I Would Die 4 U (Extended Club Mix) | Extended SMTP | Extended file system | Extended ASCII | Extended area service | Embedded Compact Extended | Chrome's address bar when visiting a site that has an Extended Validation Certificate |
With MIME, a message and all its attachments are encapsulated in a single multipart message, with base64 encoding to convert binary into 7-bit ASCII - or on modern mail servers running Extended SMTP, optionally full 8-bit support via the 8BITMIME extension.