[Dovecot] dovecot lda issue

[Joy]

I am using dovecot lda and everything is working fine for me except
the sieve rule which is built for rejecting mail from a specific
sender. message is being rejected but from address is not correct in
rejection mail which looks like the following :-

<<>@mail.xyz.net>

sieve rule :-

require ["fileinto","envelope","reject","vacation","imap4flags","relational","comparator-i;ascii-numeric","regex","body","date"];

if address :contains "From" "xyz at gmail.com"
{
reject text:
Please do not send mail to me piyush ....
.
;
}

Please let me know where is the issue with sieve rule or with lda setting :-

lda has been configured with the following parameter :-

postmaster_address = postmaster at xyz.net