Ill. Admin. Code tit. 56 § 2720.220
In any contested matter involving more than one party, the Referee shall not communicate, directly or indirectly, in connection with any issue of fact, with any interested person or party except on notice and opportunity for all parties to participate. [ 5 ILCS 100/10-60 ] If the Referee receives any such ex parte (with one party only) communication, including any documents, he or she shall inform the other parties of the substance of any such oral communication and provide copies of any such written communication or documents as soon as practicable after the communication. The other party shall be given an opportunity to respond either to any ex parte communication in writing or on the record. The e-mail address listed on a Notice of Hearing shall be used only to request to appear at a hearing in-person in accordance with Section 2720.215(b), provide contact information in advance of the hearing, request a continuance in accordance with Section 2720.240, or request a reopening in accordance with Section 2720.255. If their e-mail address is available, the other party opponent, if any, should be copied on any e-mails sent to the e-mail address listed on the Notice of Hearing. The Department's e-mail system is not secure and so social security numbers must not be included in e-mails to the e-mail address listed on the Hearing Notice (the Claimant ID or docket number should be used instead).
Ill. Admin. Code tit. 56, § 2720.220