We’re sure you’re well aware that emails are the most widely spread type of communication worldwide. Additionally, they also have the ability to send attached files.
Though emails have a built-in restriction for larger files (more than 20 or 25MB), they’re still vastly used for sending all sorts of files.
But which files can you attach?
Read on and find out how many types of email attachments are there and which ones to keep an eye out for.
What Kind Of Files Can Be Attached to an Email?
We’re all fans of the paperclip button in emails, right? And most of us know how to use it.
But, let’s discover all the possible file formats that we can actually use with this extremely beneficiary button to send through.
1. Documents
Documents are the most frequent attachments and files delivered by email as a communication tool, particularly as an official and business communication channel.
Here are all the supported document formats to send through an email:
- .doc or .docx – you create and open these files via a word processing app (like Microsoft Word). The .docx format was invented as a lighter configuration for further sharing these documents, and it’s their most recommended version when saving and sharing.
- .xsl or .xslx – documents containing graphs, tables, and spreadsheets, like those implemented from the Google Spreadsheets suite or Microsoft Excel.
- .ppt or .pptx – these documents are 99% used to save Microsoft PowerPoint Presentations.
- .pdf – digitalized documents such as this file format are usually converted from .docs and .xsl documents.
- .txt – text documents that don’t have sophisticated or any format in particular.
- .rtf – document extension similar to text documents.
- .odt – a common format of office document files usually generated by different word processing software (LibreOffice, ApacheOffice).
2. Images
Images like CV photos, ad banners, updated menus from a graphic designer, GIFs, etc., contain plenty of information.
So, here are the file formats that are supported in an email attachment:
- JPG – this is the most common image and photograph type of format that you’ll encounter.
- PNG – this format was designed especially for images on the Internet and the way they appear in web browsers.
- GIF – is an animated image.
- SVG – vector images (resizable). These can be either static or moving and animated, similar to the GIFs.
3. Media files
Media files or audiovisual content can also be shared through email attachments. Of course, each email provider has different rules regarding the maximum size of this content – since they’re the largest ones to be sent as attachments.
For example, Outlook offers 20MB, but others offer far less. Still, Gmail with up to 25MB is the absolute leader in the permitted size of files attached.
Video file formats
- .mp4 – a highly versatile, shareable, and compressed format representing the most common format in which video files appear online.
- .wmv – video file compressed using Windows Media Video compression.
- .3gp – this video format is specially designed for devices running on a 3G network.
- .flv – this format is used strictly by Adobe Flash Player.
- .mov – an mp4 format exclusively designed and configured for Apple devices.
- .m4v – another Apple video format for distributing and sharing videos on iTunes.
- .mpg – an internet format for movies, specially created to compress and stream in a faster timeframe.
- .avi – introduced and made in 1992 — this is one of the first-ever video formats to be shared on a PC and the Internet.
Audio file formats
- .mp3 – the file format that first comes to mind when sending and viewing an audio file on a device – globally supported by desktop and mobile devices.
- .wav – the main format created by Microsoft for storing audio bitstreams on a desktop computer (uncompressed files).
- .aac – or short for ‘Advanced Audio Coding’ is a widely applied audio container format for compressed digital audio and music data.
- .aif – audio format commonly used for storing CD audio files in their original quality (uncompressed).
- .ogg – a multimedia open-source file format.
- .webm – this is an open, ‘royalty-free’ media file format. It’s typically smaller than other video formats. Therefore, it’s ideal for web applications, like video streaming on popular web browsers and HTML5 videos.
4. Compressed (archive) files
The name itself reveals everything – a compressed file is a file that has been reduced in size, typically by removing unnecessary data or using a more efficient compression algorithm.
Compressed files, thus, take up less space and can easily be downloaded, making them ideal for file transfers and attachments.
There are various compression algorithms, and each one can produce a different type of compressed file.
The most common compression formats are:
- ZIP – is the most common archive data file format you can find online.
- RAR – a compressed file format archive created by WinRAR.
- 7z – powerful software that compresses data with a high compression ratio.
Which Email Attachments Are Generally Safe To Open?
We’ve decided to break it down into three tables that elaborate on all the possible email attachment types one can get to answer this question. Furthermore, we divided them into three categories: threatening, generally safe, and highly hazardous.
Safe Attachments Formats
| Format – ending letters |
Description |
Status – SAFE |
| .au |
Audio, basic |
Common |
| .avi |
video |
Common |
| .bmp |
Bit-map/ image |
Common |
| .cda |
Audio – CD format |
Common |
| .cdr |
Corel draw/ data |
Common |
| .chf |
Remote control configuration |
Not common |
| .drw |
CAD/ drawing file |
Common |
| .dwg |
CAD/ Adobe Illustrator |
Common |
| .dxf |
Universal data exchange format/ CAD |
Common |
| .eps |
Post script/ image |
Common |
| .gif |
Internet image |
Common |
| .gwf |
PCAnywhere/ Gateway file |
Not common |
| .hlp |
Help file |
Not common |
| .ht |
Hyperterminal setting file |
Not common |
| .ico |
Icon file |
Common |
| .img |
Image file |
Common |
| .iso |
CD recordable image |
Not common |
| .jpeg / .jpg |
Internet image file |
Common |
| .ldb |
MS access/ lock file |
Not common |
| .log |
Log file, generic |
Common |
| .mdb |
MS Access file |
Common |
| .mde |
MS access file/ unchangeable design |
Common |
| .mdw |
Workgroup security file |
Not common |
| .mid / .midi |
Audio MIDI file |
Common |
| .mov |
Movie – quicktime format |
Common |
| .movie |
Sgi format |
Common |
| .mp1 / .mp2 / .mp3 |
Audio mpeg format |
Common |
| .mpeg / .mpg |
Video MS format |
Common |
| .msg |
Message file |
Common |
| .nws |
Microsoft Internet News message |
Common |
| .obd |
MS Office Binder |
Common |
| .pcl |
Output to HP printer |
Not common |
| .pcx |
Black and white fax image |
Not common |
| .pdd |
Photo Deluxe format |
Common |
| .pdf |
Acrobat Reader document |
Common |
| .pic |
Image |
Common |
| .pps |
MS powerpoint slide show |
Common |
| .pub |
MS publisher data file |
Common |
| .qbb |
Intuit quick books backup file |
Common |
| .qbw |
Intuit quick books work file |
Common |
| .qdb |
Intuit quicken data file |
Common |
| .ra |
RealPlayer audio info |
Common |
| .snd |
Audio |
Common |
| .text |
Plain text |
Common |
| .tga |
Image |
Common |
| .tif |
Image |
Common |
| .tsv |
Tab-separated values |
Common |
| .txt |
Plain text |
Common |
| .wav |
Audio |
Common |
| .wma |
Audio |
Common |
| .wmf |
MS windows metafile |
Common |
| .wri |
Document MS write |
Common |
| .xlt |
MS Excel template |
Common |
Pottentially Hazardous Attachments Formats
| Format – ending letters |
Description |
Status – Caution / Low risk |
| .alx |
HTML layout |
Low risk |
| .asp |
Active server (web) page (definition) |
May contain unwanted programming – Low risk |
| .cab |
Compressed file storage |
Caution – may contain infected files |
| .cur |
Cursor (pointer) definition |
Common, Low risk |
| .dic |
Dictionary |
Caution – Low risk |
| .doc |
Microsoft Word file |
May contain threats |
| .dot |
MS Word Template – New document starting |
Low risk |
| .fav |
Outlook Navigator bar file |
Could activate a local program |
| .grp |
Windows program manager file |
Could activate a local program |
| .gtar |
Compressed file storage |
Low risk – May contain infected files |
| .gz |
Compressed file storage |
Low risk – May contain infected files |
| .htm / .html |
Web page Hypertext file |
Low risk |
| .inf |
Installation information file |
Local settings could be altered |
| .ini |
Initialization settings info |
Local settings could be altered |
| .lnk |
Short definition link |
Could activate a local program |
| .msi |
MS installer package info |
Local settings could be altered |
| .msp |
MS installer patch info |
Local settings could be altered |
| .oft |
MS outlook template |
Low risk |
| .pbk |
Phonebook, Dial up networking |
Local settings could be altered |
| .pot |
MS PowerPoint template |
May contain infected programming |
| .ppt |
MS PowerPoint data file |
Nasty programming |
| .shtml |
Security hypertext mark up file |
Low risk |
| .sys |
System information file |
Local settings could be altered |
| .tar / .tgz |
UNIX compressed file storage |
May contain infected files |
| .ttf |
True type font |
Local settings could be altered |
| .url |
Internet shortcut |
Local settings altered |
| .uu |
Internet transfer format for all files (UUEncode) |
May contain infected files |
| .vir |
Norton AV definition file |
Local settings altered |
| .wb2 |
Spreadsheet |
Nasty programming |
| .wbk |
MS Word/ Backup file |
Nasty programming |
| .wiz |
MS Word/ Wizard definition |
Nasty programming |
| .wk4 |
Spreadsheet Lotus(123) |
Nasty programming |
| .wks |
MS Excel worksheet |
Nasty programming |
| .wpd |
Word Perfect document |
Nasty programming |
| .xlk |
MS Excel/ Backup file |
Nasty programming |
| .xls |
MS Excel/ Spreadsheet book |
Nasty programming |
| .xml |
Extended markup language |
Could activate a local program |
| .z / .zip |
Compressed UNIX file storage |
Possibility of Infested files |
Dangerous Attachments Formats
| Format – ending letters |
Description |
Status – Caution / Dangerous |
| .bas |
Script, (Basic) programming language |
Common |
| .bat |
DOS batch file |
Common |
| .bin |
Octet-stream, Application |
Not common |
| .c |
C++ language programming |
Not common |
| .cmd |
Advanced batch (script) file |
Common |
| .com |
Older DOS/ Program |
Common |
| .cpl |
Control panel application |
Not common |
| .dll |
Dynamic link library (program helper file) |
Common |
| .eml |
Microsoft Internet Mail |
Common |
| .exe |
Program, executable |
Common |
| .java |
Internet universal scripting |
Not common |
| .js / .jse |
Programming (java) script |
Not common |
| .pif |
Program start info file |
Common |
| .pl |
PERL programming |
Not common |
| .reg |
Windows import/export registry |
Common |
| .scr |
Screen saver file |
Common |
| .sct |
Scriptlet file (programming) |
Not common |
| .vbe / .vbs |
Visual Basic Scripting |
Common |
| .wsc |
Scriptlet file |
Common |
| .wsf |
Script |
Not common |
| .wsh |
Windows scripting programming |
Common |
Conclusion
While you certainly can’t attach an entire movie in your email, a short link leading to the movie will deliver the message, i.e., as if you sent the entire movie.
However, hackers are aware that people send all sorts of stuff via their personal (and business) emails; hence, the reason why they try to hack into emails through these files. Or impersonate some of these files for disguising phishing links and other bedazzlement scams.
So, whenever you feel at threat – make sure to return to this article and the thorough list of email attachment files to keep an eye on.
Keep it smart, keep it safe, keep it simple — and always come back to us for some more hacks for your ultimate online security!
