Where to send letter of continued interest?

Where do I send a letter of demonstrated interest to UIUC after being deferred?

I hav sent to the email id that sent me deferral letter. No reply till nowm . I sent 31st dec

You should have an appointed Admissions Counselor. You can find his or her name on your portal (on the lower part of the first page of your myillini portal). You should send the letter to him or her.

@ccyen328 His email comes up as: admissions@illinois.edu

I found his email on UIUC directory. Should I email both places?

Does such a letter make any difference? I got deferred too from UIUC Engineering.
Also what info should one provide in such a letter?

UIUC does not want anything, such as a demonstrated interest letter, which is not in its list of materials required for applying for admission. If you send such a letter, it will not be provided to those who actually make admission decisions.

If you were deferred early action, you are still being considered for admission. When UIUC had early action before, the majority of those deferred were eventually admitted although not necessarily to the major of their choice.