%1$S is not a valid e-mail address because it is not of the form user@host. You must correct it before sending the e-mail.
Chan eil %1$S 'na sheòladh puist-dhealain a chionn 's nach eil e dhen chruth cleachdaiche@ostair. Bidh agad ri seo a chur ceart mus cuir thu am post-dealain.