just a bit more fine tuning in the wording....

checkMail.sh

@@ -12,7 +12,7 @@ hostPart=${mail/*@/}
 if [ hostPart != "localhost" ] 
 then host=$(dig +short $hostPart MX | sort -n | head -n1 | cut -d " " -f 2)
 if [ -z ${host} ]
-then echo -e "{\"status\":\"err\", \"error\":\"Unknown mail host\"}"
+then echo -e "{\"status\":\"err\", \"error\":\"Unknown mail hosti.\"}"
 exit 1
 fi
 else
@@ -43,6 +43,6 @@ then  echo "OK : " $mail >> /dev/null # $logfile
 	echo -e "{\"status\":\"ok\"}"
 	exit 0
 else echo $mail ":" $result	>> /dev/null # $logfile
-	echo -e "{\"status\":\"err\", \"error\":\"Unknown User\"}"
+	echo -e "{\"status\":\"err\", \"error\":\"Unknown username for this e-mail provider.\"}"
 	exit 1
 fi