System Characteristics
This section contains an overview of the essential characteristics of the eFax Enterprise API, including allowable message sizes, supported file types, and send transmission error codes.
Message Sizes/Payload Limits
The application provider must work within the following limitations / parameters when sending faxes:
| Parameter |
Value |
Notes |
| Maximum number of recipients per fax |
50 |
User can add more than 50 recipients per fax; however, anything above 50 is simply ignored due to configuration limitations in the send system. |
| Image resolution |
Standard or Fine |
Default value is Fine. |
| Billable retry attempts |
Minimum of 1, maximum of 10. Default is 2 attempts. |
Retry duration is set to 2 minutes. |
| Non-billable retry attempts |
Minimum of 1, maximum of 10. Default is 5 attempts. |
Retry duration is set to 2 minutes. |
| Human answer attempts |
Minimum of 1, maximum of 3 |
This is the number of retries attempted if human answer error messages are detected. This error is also counted and included in the billable counter. If set to 0 or not set, only the billable counter will be active.
|
| Attachments per fax |
Maximum of 25 |
|
| File size limits |
100MB |
This is the total maximum size of the fax payload, including base64 encoding.
|
| Supported file types |
Various |
See table of supported file types below. |
Supported Sent Transmission Error Codes
The following error codes are supported for sent transmissions:
| Status |
Description |
Billable |
Non-Billable |
| E06 |
Unspecified system error |
X |
|
| E07 |
Rast farm error |
|
X |
| E41 |
Number busy |
|
X |
| E42 |
No answer |
|
X |
| E43, E33 |
Human answer |
X |
|
| E44 |
Interrupted fax transmission |
X |
|
| E45 |
Transmission cancelled by sender |
X |
X |
| E46 |
Fax expired |
X |
|
| E49 |
Communication error |
|
X |
| E51 |
Destination fax number format invalid |
|
X |
| E52 |
High risk destination fax number |
|
X |
| E53 |
Destination fax number not allowed |
|
X |
The SFAX code indicates a successful fax transmission and is billable; it should not be considered an error code.
Supported File Types
The eFax Enterprise API supports the following file types for all outbound faxes.
Document Files
| File Type |
Software |
Details |
| DOC (MS Word Document) |
Microsoft Word, LibreOffice, Google Docs |
Older format for Word documents before DOCX. Typically contains formatted text, images, and other embedded objects. |
| DOCX (MS Word Open XML Document) |
Microsoft Word, LibreOffice, Google Docs |
More modern format, part of the Microsoft Office suite; often used for word processing. |
| DOT (MS Word Template) |
Microsoft Word |
Template version of DOC; allows for creating preformatted documents. |
| DOTX (MS Word Open XML Document Template) |
Microsoft Word |
XML-based template for Word documents.
|
| ODT (OpenDocument Text)
|
LibreOffice Writer, OpenOffice Writer
|
Open standard format for word processing documents. |
| PDF (Portable Document Format)
|
Adobe Acrobat, Foxit Reader, PDF-XChange Editor
|
Universal format for documents; often used for forms, contracts, manuals, etc. Can include text, images, and vector graphics.
For Adobe PDF, supports all PDF-types except PDF/A-3, unflattened, password protected, encrypted, or fillable. |
| RTF (Rich Text Format)
|
Microsoft Word, LibreOffice, Google Docs
|
Text format with simple formatting features (bold, italics, etc.), widely supported across platforms.
|
| TXT (Plain Text)
|
Notepad, TextEdit, Sublime Text
|
Simple text file without any formatting or media. Widely compatible.
|
| WPD (WordPerfect Document) |
Corel WordPerfect
|
Format for WordPerfect word processor; less common today but still in use in some industries.
|
Image Files
| File Type |
Software |
Details |
| BMP (Bitmap Image)
|
Microsoft Paint, Adobe Photoshop, GIMP
|
Uncompressed raster image format, large file sizes.
|
| GIF (Graphics Interchange Format)
|
Adobe Photoshop, GIMP, Microsoft Paint
|
Supports animations and simple graphics; limited to 256 colors.
|
| JPEG/JPG (Joint Photographic Experts Group)
|
Adobe Photoshop, GIMP, Microsoft Paint, Apple Preview
|
Common image format with lossy compression; ideal for photos. |
| PNG (Portable Network Graphics) |
Adobe Photoshop, GIMP, Microsoft Paint
|
Lossless compression; supports transparency.
|
| TIF/TIFF (Tagged Image File Format)
|
Adobe Photoshop, GIMP, Microsoft Paint
|
High-quality, lossless image format, often used in professional photography and scanning.
|
| PSD (Adobe Photoshop Document)
|
Adobe Photoshop
|
Photoshop's native format; supports layers and high-quality image editing. |
| WPG (WordPerfect Graphic)
|
Corel WordPerfect, CorelDRAW
|
Vector graphic
|
Spreadsheet / Data Files
| File Type |
Software |
Details |
| CSV (Comma-Separated Values)
|
Microsoft Excel, Google Sheets, LibreOffice Calc
|
Plain text format for tabular data, with commas separating values.
|
| XLS (Microsoft Excel Spreadsheet)
|
Microsoft Excel, LibreOffice Calc, Google Sheets
|
Older Excel format (pre-2007), supports data, formulas, charts
|
| XLSX (Microsoft Excel Open XML Spreadsheet)
|
Microsoft Excel, LibreOffice Calc, Google Sheets
|
XML-based format for Excel spreadsheets, supports advanced features like charts and pivot tables.
|
| ODS (OpenDocument Spreadsheet)
|
LibreOffice Calc, OpenOffice Cal
|
Open standard for spreadsheets.
|
Document / Data Files
| File Type |
Software |
Details |
| XML (Extensible Markup Language)
|
Any text editor, XML parsers (e.g., XMLSpy, Notepad++)
|
Used for structured data exchange between systems; can include both text and metadata.
|
| XSD (XML Schema Definition)
|
XML parsers, IDEs (e.g., Visual Studio)
|
Defines the structure and constraints of XML data.
|
| XSI (XML Schema Instance) |
XML parsers
|
An instance of data based on an XSD schema.
|
Document / Web Page Files
| File Type |
Software |
Details |
| HTML/HTM (Hypertext Markup Language)
|
Any text editor, web browsers, IDEs (e.g., Visual Studio Code, Sublime Text)
|
The standard for creating web pages; can be opened in browsers.
|
| MHTM/MHTML (MHTML Archive)
|
Web browsers (Microsoft Edge, Chrome), Internet Explorer
|
A web page archive that includes HTML and associated resources like images.
|
Document / Source Code Files
| File Type |
Software |
Details |
| C/CPP (C and C++ Source Code)
|
IDEs (Visual Studio, Eclipse, CLion)
|
Source code files for C and C++ programming languages.
|
| H (C/C++ Header File)
|
IDEs (Visual Studio, Eclipse)
|
Header files used in C/C++ programming, typically defining function prototypes and constants.
|
Document / Text and Log Files
| File Type |
Software |
Details |
| MD (Markdown)
|
Markdown editors, GitHub, Visual Studio Code
|
Lightweight markup language used for formatting text, often used in documentation and code repositories.
|
| ERR (Error Log or Report)
|
Text editors, log viewers
|
Often used for logging errors in software or systems
|
Presentation Files
| File Type |
Software |
Details |
| PPT (Microsoft PowerPoint Presentation)
|
Microsoft PowerPoint, LibreOffice Impress, Google Slide
|
Classic PowerPoint format, used for creating slideshows.
|
| PPTX (Microsoft PowerPoint Open XML Presentation)
|
Microsoft PowerPoint, LibreOffice Impress, Google Slides
|
Modern PowerPoint format based on XML; supports richer multimedia content.
|
Diagram Files
| File Type |
Software |
Details |
| VSD (Microsoft Visio Drawing)
|
Microsoft Visio
|
Visio's legacy format for diagrams, flowcharts, and schematics.
|
| VSDX (Microsoft Visio Open XML Drawing)
|
Microsoft Visio
|
Newer format for Visio, supports richer diagrams and integration with other Office apps.
|
Miscellaneous Files
| File Type |
Software |
Details |
| ODG (OpenDocument Graphics)
|
LibreOffice Draw, OpenOffice Draw
|
Open standard format for vector graphics, part of the OpenDocument suite.
|
| ODP (OpenDocument Presentation)
|
LibreOffice Impress, OpenOffice Impress
|
Open standard for creating presentations.
|
| PUB (Microsoft Publisher Document)
|
Microsoft Publisher
|
Used for creating brochures, newsletters, and other marketing materials.
|
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