Allowed attachment types for sending email in Azure Communication Services Email

The Send Email operation allows the option for the sender to add attachments to an outgoing email. Along with the content itself, the sender must include the file attachment type using the MIME standard when making a request with an attachment. Many common file types are accepted, such as Word documents, Excel spreadsheets, many image and video formats, contacts, and calendar invites.

What is a MIME type?

MIME (Multipurpose Internet Mail Extensions) types are a way of identifying the type of data that is being sent over the internet. When users send email requests with Azure Communication Services Email, they can specify the MIME type of the email content, which allows the recipient's email client to properly display and interpret the message. If an email message includes an attachment, the MIME type would be set to the appropriate file type (for example, "application/pdf" for a PDF document).

Developers can ensure that the recipient's email client properly formats and interprets the email message by using MIME types, irrespective of the software or platform being used. This information helps to ensure that the email message is delivered correctly and that the recipient can access the content as intended. In addition, using MIME types can also help to improve the security of email communications, as they can be used to indicate whether an email message includes executable content or other potentially harmful elements.

To sum up, MIME types are a critical component of email communication, and by using them with Azure Communication Services Email, developers can help ensure that their email messages are delivered correctly and securely.

Allowed attachment types

Here's a table listing some of the most common supported file extensions and their corresponding MIME types for email attachments using Azure Communication Services Email:

File Extension Description MIME Type
.3gp 3GPP multimedia file video/3gpp
.3g2 3GPP2 multimedia file video/3gpp2
.7z 7-Zip compressed file application/x-7z-compressed
.aac AAC audio audio/aac
.avi AVI video file video/x-msvideo
.bmp BMP image image/bmp
.csv Comma-separated values text/csv
.doc Microsoft Word document (97-2003) application/msword
.docm Microsoft Word macro-enabled document application/
.docx Microsoft Word document (2007 or later) application/vnd.openxmlformats-officedocument.wordprocessingml.document
.eot Embedded OpenType font application/
.epub EPUB ebook file application/epub+zip
.gif GIF image image/gif
.gz Gzip compressed file application/gzip
.ico Icon file image/
.ics iCalendar file text/calendar
.jpg, .jpeg JPEG image image/jpeg
.json JSON data application/json
.mid, .midi MIDI audio file audio/midi
.mp3 MP3 audio file audio/mpeg
.mp4 MP4 video file video/mp4
.mpeg MPEG video file video/mpeg
.oga Ogg audio file audio/ogg
.ogv Ogg video file video/ogg
.ogx Ogg file application/ogg
.one Microsoft OneNote file application/onenote
.opus Opus audio file audio/opus
.otf OpenType font font/otf
.pdf PDF document application/pdf
.png PNG image image/png
.ppsm PowerPoint slideshow (macro-enabled) application/
.ppsx PowerPoint slideshow application/vnd.openxmlformats-officedocument.presentationml.slideshow
.ppt PowerPoint presentation (97-2003) application/
.pptm PowerPoint macro-enabled presentation application/
.pptx PowerPoint presentation (2007 or later) application/vnd.openxmlformats-officedocument.presentationml.presentation
.pub Microsoft Publisher document application/
.rar RAR compressed file application/x-rar-compressed
.rpmsg Outlook email message application/
.rtf Rich Text Format document application/rtf
.svg Scalable Vector Graphics image image/svg+xml
.tar Tar archive file application/x-tar
.tif, .tiff Tagged Image File Format image/tiff
.ttf TrueType Font font/ttf
.txt Text Document text/plain
.vsd Microsoft Visio Drawing application/vnd.visio
.wav Waveform Audio File Format audio/wav
.weba WebM Audio File audio/webm
.webm WebM Video File video/webm
.webp WebP Image File image/webp
.wma Windows Media Audio File audio/x-ms-wma
.wmv Windows Media Video File video/x-ms-wmv
.woff Web Open Font Format font/woff
.woff2 Web Open Font Format 2.0 font/woff2
.xls Microsoft Excel Spreadsheet (97-2003) application/
.xlsb Microsoft Excel Binary Spreadsheet application/
.xlsm Microsoft Excel Macro-Enabled Spreadsheet application/
.xlsx Microsoft Excel Spreadsheet (OpenXML) application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
.xml Extensible Markup Language File application/xml, text/xml
.zip ZIP Archive application/zip

There are many other file extensions and MIME types that can be used for email attachments. However, this list includes accepted types for sending attachments in our SendMail operation. Additionally, different email clients and servers may have different limitations or restrictions on file size and types that could result in the failure of email delivery. Ensure that the recipient can accept the email attachment or refer to the documentation for the recipient's email providers.

Additional information

The Internet Assigned Numbers Authority (IANA) is a department of the Internet Corporation for Assigned Names and Numbers (ICANN) responsible for the global coordination of various Internet protocols and resources, including the management and registration of MIME types.

The IANA maintains a registry of standardized MIME types, which includes a unique identifier for each MIME type, a short description of its purpose, and the associated file extensions. For the most up-to-date information regarding MIME types, including the definitive list of media types, it's recommended to visit the IANA Website directly.

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