When sending emails, the following Mime Types and File Extensions are supported for attachments:

Mime Types/File ExtensionsFormat
aac
"audio/aac"
abw
"application/x-abiword"
arc
"application/x-freearc"
avif
"image/avif"
avi
"video/x-msvideo"
azw
"application/vnd.amazon.ebook"
bin
"application/octet-stream"
bmp
"image/bmp"
bz
"application/x-bzip"
bz2
"application/x-bzip2"
cda
"application/x-cdf"
csh
"application/x-csh"
css
"text/css"
csv
"text/csv"
doc
"application/msword"
docx
"application/vnd.openxmlformats-officedocument.wordprocessingml.document"
eot
"application/vnd.ms-fontobject"
epub
"application/epub+zip"
gz
"application/gzip"
gif
"image/gif"
htm
"text/html"
html
"text/html"
ico
"image/vnd.microsoft.icon"
ics
"text/calendar"
jar
"application/java-archive"
jpeg
"image/jpeg", "application/photoshop"
jpg
"image/jpeg", "application/photoshop"
js
"text/javascript"
json
"application/json"
jsonld
"application/ld+json"
mid
"audio/midi","audio/x-midi"
midi
"audio/midi","audio/x-midi"
mjs
"text/javascript"
mp3
"audio/mpeg"
mp4
"video/mp4"
mpeg
"video/mpeg"
mpkg
"application/vnd.apple.installer+xml"
msg
"application/vnd.ms-outlook"
odp
"application/vnd.oasis.opendocument.presentation"
ods
"application/vnd.oasis.opendocument.spreadsheet"
odt
"application/vnd.oasis.opendocument.text"
oga
"audio/ogg"
ogv
"video/ogg"
ogx
"application/ogg"
opus
"audio/opus"
otf
"font/otf"
png
"image/png"
pdf
"application/pdf"
php
"application/x-httpd-php"
ppt
"application/vnd.ms-powerpoint"
pptx
"application/vnd.openxmlformats-officedocument.presentationml.presentation"
rar
"application/vnd.rar"
rtf
"application/rtf"
sh
"application/x-sh"
svg
"image/svg+xml"
tar
"application/x-tar"
tif
"image/tiff"
tiff
"image/tiff"
ts
"video/mp2t"
ttf
"font/ttf"
txt
"text/plain"
vsd
"application/vnd.visio"
wav
"audio/wav"
weba
"audio/webm"
webm
"video/webm"
webp
"image/webp"
woff
"font/woff"
woff2
"font/woff2"
xhtml
"application/xhtml+xml"
xls
"application/vnd.ms-excel"
xlsx
"application/vnd.ms-excel", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
xml
"application/xml", "text/xml" , "application/atom+xml"
xul
"application/vnd.mozilla.xul+xml"
zip
"application/zip"
3gp
"audio/3gpp", "video/3gpp"
3g2
"audio/3gpp2", "video/3gpp2"
7z
"application/x-7z-compressed"