Tested on Debian GNU/Linux amd64, LibreOffice 3.5.5.3 .deb packages downloaded from www.libreoffice.org (not the ones provided by Debian).
1) Menu Tools / Options / Internet / E-mail
2) Enter /usr/bin/mutt for field "E-mail program"
3) Click on "OK"
4) Send as PDF from a Base report works
Tested on Debian GNU/Linux amd64, LibreOffice 3.5.5.3 .deb packages downloaded from www.libreoffice.org (not the ones provided by Debian).
1) Menu Tools / Options / Internet / E-mail
2) Enter /usr/bin/mutt for field "E-mail program"
3) Click on "OK"
4) Send as PDF from a Base report works