YouMail Inc.'s popular digital secretary that answers mobile voicemail has handled 500 million calls as of August and manages 1.5 million calls daily.

YouMail founder and chief executive Alex Quilici attributed the success of the mobile application to the convenience it affords subscribers now numbering more than one million.

The app is most popular in BlackBerry smartphones being the top "productivity" download. In Palm devices, YouMail's YouView visual voicemail app is the top paid application.

Also driving YouMail's growth is its use by regional wireless VOIP carriers in the U.S. IMMIX Wireless in Pennsylvania, Cellular One in East Central Illinois, Blue Wireless in New York, iSmart Mobile in Montana, VoicePulse in New Jersey, and Windy City Cellular in Adak, Alaska provide voicemail service using YouMail.

With YouMail, a missed call will be dialed so a pre-recorded, tailored message or greetings can be sent to the caller. It also has a "DitchMail" feature that greets unwanted callers before automatically disconnecting the call.

YouMail has an online community that shares numbers of telemarketers so users can block calls from them.

Greetings, including notable ones from movies and in foreign languages, can also be downloaded from the YouMail website for use in various occasions.

YouMail also provides transcription service for those who want their voicemail converted into text.

The voicemail answering function of YouMail is compatible with voice messages from VOIP service providers such as Google Voice, MagicJack, OOMA, and Vonage.

Post-paid mobile users in the U.S. can get basic YouMail service for free.