Section 735 ILCS 5/2-205 - Service on partnership and partners(a) A partnership sued in its firm name may be served by leaving a copy of the process with any partner personally or with any agent of the partnership found anywhere in the State. A partnership sued in its firm name may also be notified by publication and mail in like manner and with like effect as individuals.(b) When a personal judgment is sought against a known partner for a partnership liability the partner may be served (1) in any manner provided for service on individuals or (2) by leaving a copy of the summons for him or her with any other partner and mailing a copy of the summons in a sealed envelope with postage prepaid, addressed to the partner against whom the judgment is sought at his or her usual place of abode as shown by an affidavit filed in the cause. The certificate of the officer or the affidavit of the other person making service that he or she has mailed the copy in pursuance of this section is evidence that he or she has done so. Service on a nonresident partner against whom a personal judgment is sought may be made by leaving a copy with any other partner, and mailing, as provided herein, only if the cause of action sued on is a partnership liability arising out of the transaction of business within the State.(c) When a personal judgment is sought against an unknown owner in an action authorized under Section 6 of "An Act in relation to the use of an assumed name in the conduct or transaction of business in this State", approved July 17, 1941, as amended, service may be made by leaving a copy of the summons with any agent of the business and publishing notice in the manner provided by Section 2-206 of this Act.