they're disabled by default, and so it's impossible to forward mails to another mailserver which needs authentication
Created attachment 6041 [details] patch to enableAUTH_PLAINTEXT and AUTH_CRAM_MD5
Your patch looks good. Can you submit it as a Git formatted patch to the Buildroot mailing list, by following the instructions at http://buildroot.org/downloads/manual/manual.html#submitting-patches ? Thanks!
Patch committed as 924578ae03cfbb49264f1d0cc31a214026a67b84, thanks!