LR-IMAP protocol Logon issue

I need to login to mail box using IMAP protocol. Below are my login details

Mailbox id: abcd@xxx.com

Username: abcdefg

Password: zzzzzz

I don’t have option to input all this 3 details via imap_logon. I can only input Address and Password like I don’t have argument Option to input username

imap_logon("ImapLogon",

                                                "URL=imaps://abcd@xxx.com:zzzzzz@imap.exchangeserver.com:993",

                                                LAST);

Kindly suggest me the correct Argument to input my username