cubicweb #1022819 mass mailing error [open]

I clicked 'send' and got "not enough argument for format string". There is no way to recover from this error. The text is lost and the user can not figure out what failed exactly, wrong email address ? wrong substitution variable ? something else ? Improve this.

priorityminor
typebug
done in<not specified>
load0.300
load left0.300
closed by<not specified>