I have a list of email addresses in one file, each on its own line.

I'm trying to output them to another file as a list separated by commas. Here is the code in question.
Code:
while (chomp($line = <MEMBER_LIST>))
{
  print D_LIST $line . ',';
}
It gives me the email address separated by commas like I want, but it also throws in a "^M" after each address.

Like:
[email protected]^M,[email protected]^M,[email protected]^M,...

When I change that comma in the code to a newline character, the "^M" disappears. Any idea on why it's doing this?