The Internet Messaging Program or IMP is a webmail client. It can be used to access e-mail stored on an IMAP server. IMP is written in PHP and a component of the collaborative software suite Horde.
HTML message composition with a cross-browser WYSIWYG editor
Drag/drop attachment support into WYSIWYG editor
HTML signatures
High performance
Robust IMAP support, utilizing advanced server features
Flexible message search
Address autocompletion
Spell checking
Sending of attachments via download link, instead of embedding in message
Thread view
Message previews in mailbox view
Desktop like user interface and navigation (also via keyboard)
IMAP folder support
Management of shared IMAP folders (ACLs)
Folder subscriptions
Various identities
Alias and "tied to" addresses in user identities
Integration with e-mail filtering
Integration with addressbook
Integration with calendar
S/MIME and PGP based encryption and signatures
Mailbox quotas
Ability to forward multiple messages at once
Download of attachments as ZIP archive
Stripping of attachments from messages
Preview of attachments in compose view
Priority settings for composed messages
Message flags
Graphical emoticons and country flags in message view
Available in many languages
Full charset support
History
Chuck Hagenbuch published a first version of IMP on Freshmeat in 1998.[3] A constant stream of feature requests not all fitting for a webmail application led to the development of a more generic web application backbone: the Horde framework. The release of IMP 3.0 and Horde 2.0 was the first one with two truly separate components.[4] Since then any deployment of IMP can only run on top of a Horde installation.
SAPO uses IMP[5] to provide several million users with a webmail platform.[6] The company also sponsored the initial development of the dynamic AJAX variant of IMP[7] which was released as a separate package - named DIMP - with the release of Horde 3.2.[8][9]
Support for mobile clients was provided within 2006 for the first time. At that time a WAP based mobile view was provided by a separate package called MIMP.[10]
With the release of Horde 4.0 the three existing views were collapsed into the original IMP package again. In addition another mobile view for smartphones was added based on the jQuery MobileJavaScript framework.[11][12]