File types you can attach
Which files an email letter can carry, which are refused and why, and which the recipient can view in the browser.
4 minutes to read
Files and recordings travel with email letters. A paper letter carries text only. How large a file may be and how many you can attach depends on your plan, see All limits in one place.
Files you can attach
| Kind | Types |
|---|---|
| Images | JPEG, PNG, GIF, WebP, AVIF, HEIC, SVG, BMP, TIFF, ICO and any other image format your browser knows |
| Video | MP4, WebM, MOV, MKV, AVI, MPEG and any other video format your browser knows |
| Audio | MP3, WAV, OGG, M4A, AAC, FLAC, WMA and any other audio format your browser knows |
| PDF and office documents | PDF, Word (.doc, .docx), Excel (.xls, .xlsx), PowerPoint (.ppt, .pptx), RTF and OpenDocument (.odt, .ods, .odp) |
| Text and data | Plain text, CSV, Markdown, HTML, CSS, JSON and XML |
| Archives | ZIP, RAR, 7z, TAR and GZIP |
| Other files | A file your browser reports no type for, such as the format of a special program. It is accepted unless its ending is on the list of refused files |
A voice or video message you record in the composer with Voice or Video is attached as an audio or video file. Depending on your browser it is a WebM file, or an MP4 file for video and an M4A file for voice.
How the type is decided
- The ending of the name is checked first. A file with an ending from the list of refused files is never accepted.
- Then the type your browser reports is checked. Every image, video, audio and text type is accepted. For other files, only the types in the table are. The names that Windows uses for ZIP, RAR and GZIP archives are accepted as well.
- A file your browser reports no type for is judged by its ending alone.
The composer and the server apply the same rule. A file the composer lets you add is not refused for its type when you send.
Files that are refused
Programs and scripts cannot be sent, because a recipient could run them by opening the file. A file with one of these endings is refused whatever type the browser reports:
| Kind | Endings |
|---|---|
| Windows programs and installers | .exe, .msi, .com, .scr, .pif, .bat, .cmd |
| Scripts | .js, .jse, .vbs, .vbe, .ps1, .psm1, .ws, .wsf, .wsc, .wsh, .hta |
| Shell scripts | .sh, .bash, .csh, .ksh |
| Java programs | .jar, .class, .war |
| System files | .dll, .sys, .drv, .reg, .inf, .cpl, .msc |
View in the browser or download
On the page where the recipient reads the letter, each file has a View button, a Download button or both. Which ones depends on the type of the file and on the sharing settings you chose in the composer, with Change under Attachments.
| File | On the recipient's page |
|---|---|
| JPEG, PNG, GIF, WebP, AVIF, BMP and SVG images | Shown on the page |
| Other images, such as TIFF, ICO and HEIC | Download only |
| Video and audio | Played on the page, when the recipient's browser can play the format |
| Shown on the page | |
| Text and data files | Shown as plain text. An HTML or XML file is shown as its source text and never runs as a web page |
| Office documents, archives and everything else | Download only |
- View and download
- The recipient can view the files that can be shown and download all of them. This is the setting when you change nothing.
- Download only
- No file is shown on the page. Every file can be downloaded.
- View online only
- Files that can be shown are shown and have no download button. A file that cannot be shown in a browser, a ZIP archive for example, is still offered as a download. Otherwise the recipient could not get it at all.
When a recipient has used every download you allow, Download gives way to Limit reached. Viewing and playing stay possible until the link expires. How the sharing settings and the download limit work is explained in Control how recipients open your files.
What can go wrong
| What you see | Why | What to do |
|---|---|---|
| A message that the file is not a file type we can send, when you add it | The ending of the file is on the list of programs and scripts, or your browser reports a type that is not in the table. | A program or a script cannot be sent. Save any other file in a common format such as PDF, or put it in a ZIP archive. |
| A file of a kind in the table is refused | Some systems report an unusual type for a common file. | Try another browser. If it is still refused, contact us and tell us the kind of file. |
| The recipient sees that the file could not be shown, or that the browser cannot play it | The recipient's browser does not support the format. | The recipient can download the file instead, unless you chose View online only. |
- Attach files and recordings to an email letterAdd documents, photos, or a voice or video message recorded in your browser. What your plan allows, when files are uploaded and what happens at the limits.
- Control how recipients open your filesDecide whether the files of a letter can be viewed online, downloaded or both, how often and for how long. Then follow, extend or delete them on the Files page.
- All limits in one placeEvery limit of FuturePostman on one page: plans, files, email letters, paper letters, public letters, link times and attempt limits.
- How your letters are protectedWhat FuturePostman encrypts, how a recipient proves who they are, when a link stops working, what staff can see and where the protection ends.