Closes #338
Closes #338

In case of non-existing user return cb(false) as expected.
niteoweb/Haraka,niteoweb/Haraka,Synchro/Haraka,hiteshjoshi/my-haraka-config,smfreegard/Haraka,danucalovj/Haraka,danucalovj/Haraka,abhas/Haraka,abhas/Haraka,hiteshjoshi/my-haraka-config,msimerson/Haraka,Dexus/Haraka,AbhilashSrivastava/haraka_sniffer,haraka/Haraka,fredjean/Haraka,haraka/Haraka,AbhilashSrivastava/haraka_sniffer,DarkSorrow/Haraka,pedroaxl/Haraka,msimerson/Haraka,Synchro/Haraka,fredjean/Haraka,DarkSorrow/Haraka,hatsebutz/Haraka,msimerson/Haraka,jaredj/Haraka,haraka/Haraka,MignonCornet/Haraka,haraka/Haraka,baudehlo/Haraka,MignonCornet/Haraka,pedroaxl/Haraka,fatalbanana/Haraka,bsmr-x-script/Haraka,typingArtist/Haraka,craigslist/Haraka,baudehlo/Haraka,slattery/Haraka,jjz/Haraka,MignonCornet/Haraka,xming/Haraka,fatalbanana/Haraka,DarkSorrow/Haraka,bsmr-x-script/Haraka,msimerson/Haraka,slattery/Haraka,fatalbanana/Haraka,fatalbanana/Haraka,craigslist/Haraka,xming/Haraka,MignonCornet/Haraka,jaredj/Haraka,craigslist/Haraka,danucalovj/Haraka,jaredj/Haraka,hatsebutz/Haraka,zombified/Haraka,zombified/Haraka,smfreegard/Haraka,slattery/Haraka,zombified/Haraka,typingArtist/Haraka,slattery/Haraka,Dexus/Haraka,niteoweb/Haraka,armored/Haraka,hatsebutz/Haraka,AbhilashSrivastava/haraka_sniffer,Synchro/Haraka,craigslist/Haraka,Dexus/Haraka,hatsebutz/Haraka,hiteshjoshi/my-haraka-config,typingArtist/Haraka,danucalovj/Haraka,DarkSorrow/Haraka,jjz/Haraka,Dexus/Haraka,bsmr-x-script/Haraka,smfreegard/Haraka,jjz/Haraka,smfreegard/Haraka,zombified/Haraka,abhas/Haraka,baudehlo/Haraka,armored/Haraka,bsmr-x-script/Haraka,fredjean/Haraka,Synchro/Haraka,jaredj/Haraka,pedroaxl/Haraka,baudehlo/Haraka,armored/Haraka,jjz/Haraka,AbhilashSrivastava/haraka_sniffer,typingArtist/Haraka