Developed By BlueRabbIT

Compatible with WHMCS v8.9

Stop mailing invoices yourself

Our world is becoming more and more digital but let's face it, many customers request an invoice being sent by snail mail.

This means printing out the invoice, folding it, preparing the envelope, and mailing it.

Wouldn't it be nice if someone else could take care of this for you?

This is where comes in!

About is a web based Hybrid Mail service to efficiently, economically and ecologically send letters locally and the rest of the world.

Best prices and fastest deliveries are automatically available thanks to their international printing network.

What we offer

Our module offers a seamless integration of the service in your WHMCS installation.

This allows you to send invoices to your customers in a professional manner, saving you the time and the hassle of printing and mailing the invoices yourself.

Plenty of features

  • Send invoices and quotes via, manually or automatically
  • Automatic sending based on payment gateways and product addons
  • Manage and track your sendings from within WHMCS
  • Fully configurable
  • Supports the BlueRabbIT BestPDF Addon
  • Supports the BlueRabbIT Swiss QR Addon for sending Swiss payment slips

Actively maintained

This product is actively maintained and we use it ourselves.

We are here to listen, so if you have any requests or problems, we will be happy to assist you and further improve the product.



5 stars
4 stars
3 stars
2 stars
1 star

Chris Mayer @chris6796

December 28, 2020 at 02:02:03 PM

Wir haben dieses Module nun seit ein paar Wochen im Einsatz und können das Modul wie auch BlueRabbit zu 100% empfehlen, denn auch der Support ist sehr gut und schnell! Mit diesem Modul gelingt der Versand von Rechnungen aus WHMCS via Pingen einfach, gut und mir sehr nützlichen Zusatzfeatures. Wir sind sehr froh, dass es nun doch jemanden gibt der solche eher schweizerische Module für WHMCS macht.

Sebastian Vassiliou @BlueRabbIT

May 11, 2022 at 09:37:34 AM

Vielen Dank für die positive Bewertung. Es freut mich sehr, dass das Modul gut ankommt!

  • 3 years ago
  • Version Number 3.3.0

Igi Vuillemier @igi3142

April 14, 2020 at 11:10:54 AM

this module is absolutely brilliant, the developer works cleanly, exactly very quickly and very reliably. I can only recommend it, therefore 5 stars out of 5.
Thank you for this very useful module.

Sebastian Vassiliou @BlueRabbIT

May 11, 2022 at 09:36:36 AM

Thank you very much for your five stars! Glad you like the module :)

  • 4 years ago
  • Version Number 3.0.1

Version Compatibility

Compatible with WHMCS v8.9

Full Version Compatibility

  • Selected versions of WHMCS v8.9
  • Selected versions of WHMCS v8.8
  • All versions of WHMCS v8.7
  • All versions of WHMCS v8.6
  • All versions of WHMCS v8.5
  • All versions of WHMCS v8.4
  • All versions of WHMCS v8.3
  • All versions of WHMCS v8.2
  • All versions of WHMCS v8.1
  • All versions of WHMCS v8.0
  • All versions of WHMCS v7.10
  • All versions of WHMCS v7.9
  • All versions of WHMCS v7.8
  • All versions of WHMCS v7.7
  • All versions of WHMCS v7.6
  • All versions of WHMCS v7.5

System Requirements

  • A account

* Requirements listed are in addition to the WHMCS default system requirements.

Support for this product

The best place to start if you need help with a specific product is to contact the developer. All WHMCS Marketplace developers have both a website and support URL listed.

Developed By BlueRabbIT


v5.1.1 Released January 15th, 2024

Latest Version

  • Update to latest Pingen SDK
  • Fix license check fsock fallback mode
  • Fix error handling on modal submissions
  • Fix letters table not being reloaded on certain actions


Previous Versions

v5.1.0 Released January 30th, 2023

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  • Reintroduced calculator utility
  • Fix hooks loading libs unnecessarily


v5.0.0 Released November 28th, 2022

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  • Compatible with the new Pingen API - WARNING! please read the enclosed README file before upgrading!


v4.1.0 Released November 7th, 2022

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  • Add compatibility with WHMCS 8.6 and PHP 8.1


v4.0.2 Released August 3rd, 2021

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  • Fix module failing to activate in some cases


v4.0.1 Released April 26th, 2021

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Fix invoice being sent in client mode if client is set to default


v4.0.0 Released April 14th, 2021

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  • Add the ability to add fee to each newly created invoice
  • Documents are now shown in modals
  • Add trigger option to send only when order is accepted
  • Documents now show more details
  • Implemented server-side pagination on all tables for better performance
  • Add option to send invoice when late fee is added
  • Make sure to only send invoices which are unpaid
  • Add button for synchronizing documents
  • Moved calculator to modal in send center
  • Moved document upload to modal in documents page
  • Converted UI to single page application for better responsiveness
  • Handle errors in data tables
  • Code overhaul with automated code quality checks
  • Calculator adapts to speeds available for selected country
  • Also save sent document ID on send
  • Don’t send envelope ID for unsupported countries
  • Allow clients to configure invoice delivery from the Client Area
  • Implement WHMCS metadata
  • Fix calculator documents dropdown not affecting anything
  • Fix hook not reacting if the WHMCS option “No Invoice Email on Order” is enabled
  • Fix deleted documents remaining in DB
  • Fix send mode not respected in invoice list status column


v3.3.0 Released August 20th, 2020

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  • Added WHMCS v8 and PHP 7.4 compatibility


v3.2.0 Released June 1st, 2020

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  • Sendcenter now synchronizes with local tables
  • Now showing all sent invoices and quotes
  • Fixed Print Mode and Address Position settings not working properly


v3.1.0 Released April 20th, 2020

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  • Show more detailed tracking information
  • Fixed sentquotes table not being dropped on module deactivation


v3.0.1 Released March 23rd, 2020

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  • Show spinner and disable button while sending
  • Invoice button says Resend if invoice was already sent
  • Fixed hooks not working on some systems
  • Fixed hooks not working on some systems
  • Fixed send to Pingen via invoice no longer working
  • Fixed Widget no longer showing up in Admin Roles configuration
  • Fixed GUI showing success on failure


v3.0.0 Released March 17th, 2020

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  • Added ability to send Quotes
  • Complete code refactoring
  • Improved error handling
  • Use date format as configured in WHMCS
  • Fixed table state saving not working properly
  • Now compatible with our BestPDF 2.0 module


v2.2.0 Released February 26th, 2020

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  • Added option to avoid sending invoices when balance is 0
  • Properly handle client setting Never when Automatic mode is on
  • Added ability to abort sending e-mails when sending via Pingen
  • Added ability to send on overdue notices
  • Fixed sidebar saying production mode was active even if staging was
  • Updated Pingen API
  • PHP 7.1 is now the minimum required version


v2.1.0 Released January 20th, 2020

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  • Made simplex/duplex print mode configurable
  • Made left/right address position configurable
  • Implemented send button on invoice edit page
  • Made storage path configurable
  • Implemented client profile setting for sending invoices on a per-customer basis
  • Fixed United States not being detected by Pingen
  • Updated Pingen API
  • Updated bundled BestPDF module to version 1.1.1


v2.0.1 Released November 15th, 2019

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  • Fixed addon setting not always working properly
  • Updated Pingen API
  • Updated bundled BestPDF module to version 1.1.0


v2.0.0 Released November 28th, 2018

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  • Integration with our BestPDF module
  • Integration with our PostFinance ISR module
  • Implemented full localization to German, French and Italian
  • Added option to specify Envelope Design ID
  • Also send automatically when overdue charges are added to invoice
  • Save sent date for invoices
  • Use DataTables for table output
  • Views are now in Smarty Templates
  • Improved status display in invoices list
  • Improved dialogs and feedback messages
  • Improved sending speed handling
  • Improved configuration
  • Adaptations for new BlueRabbIT licensing server
  • Some minor bug fixes
  • Now requires at least WHMCS 7.0 and ionCube loader 10.1


See also

Accept Bitcoin and cryptocurrency payments - CoinGate for WHMCS

Easily accept Bitcoin, Tether, Ethereum and many other crypto payments on your WHMCS website

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Send account statements to customers

GST WHMCS Module For India

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Handling Fees

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Discount Center For WHMCS

Introduce discounts applicable to orders of specified products combinations or quantities.