Case insensitive mails in sendmail - user unknown error

I am using sendmail for my domain . I have created a email id like selvA@hiox.org . But when the mails are send to selvA@hiox.com , sendmail provides the error user unknown . Then i reffered the senamil documents and found that to make sendmail as case sensitive the configuration option MODIFY_MAILER_FLAGS(`LOCAL', `+u')dnl must be added to sendmail.mc .This option makes sendmail to consider local part of email id with case sensitive. I have added this option and complied sendmail and restart started it now the mail for selvA@hiox.org is delivering properly .