filename myinput "c:\emails.txt";
filename myoutput "c:\parsed.txt";

data _null_;                    /* not creating a SAS dataset */
infile myinput;                           /* input a flatfile */
file myoutput;                           /* output a flatfile */

length email $40;
input email $;                        /* input has email only */

atsign = index(email,"@");             /* position of at sign */
name = substr(email,1,atsign-1);     /* name preceded at sign */
remains = substr(email,atsign+1);              /* what's left */
period = index(remains,".");          /* period after at sign */
domain = substr(remains,1,period-1);        /* isolate domain */
type = substr(remains,period+1);       /* type follows period */

put @1 name $20. @21 domain $20. @41 type $3.;    /* write it */

run;