Dear Maintainer,

icedove requires libcanberra0 to play new mail notification sounds, yet it
doesn't depend on libcanberra0 anyway. It should at least suggest, maybe even
recommend libcanberra0 package.

Steps to reproduce:
- Uninstall libcanberra0 if installed
- Run icedove, go to menu -> edit -> preferences -> general -> when new
  messages arrive -> select a sound and click "Play"

Current outcome:
- Nothing sounds
- No error message, no error in menu -> tools -> error console, nothing printed
  to stderr/stdout

Expected outcome:
- Plays sound (that happens when libcanberra0 is installed)
- Otherwise display an error with suggestion to install libcanberra0 (wishlist,
  no need with current bug :) )

Solution:
- Add libcanberra0 to icdedove package's Recommends

Thank you and best regards

Pavel