Short answer. You may serve it by registered mail or by substituted service. Rule 122, Section 4 allows this when personal service of the notice of appeal cannot be made on the adverse party or counsel, following the procedures for registered mail or substituted service set out in Rule 13, Sections 7 and 8.
What the law says
If personal service of the copy of the notice of appeal can not be made upon the adverse party or his counsel, service may be done by registered mail or by substituted service pursuant to sections 7 and 8 of Rule 13.
Rule 122, Section 4 — Service of notice of appeal. Read the full provision →
Personal service is the default, not the only option
Section 4 assumes personal service is ordinarily how a copy of the notice of appeal reaches the adverse party or counsel, but it does not make that the only path. Where personal service genuinely cannot be accomplished, the rule opens two fallback methods rather than leaving the appellant stuck. Section 4 only opens once personal service has genuinely proven impossible, rather than being available as a matter of convenience. A party who skips straight to an improvised method without first attempting personal service risks the very defect this rule is designed to avoid.
The two fallback methods
The section points to registered mail and substituted service, both governed by Sections 7 and 8 of Rule 13. Registered mail service is completed according to the mechanics of Rule 13's mailing provisions, while substituted service follows that rule's procedure for reaching a party or counsel indirectly when direct service fails. Choosing the correct method under Rule 13, rather than an ad hoc alternative, is what makes the service effective under Section 4.
Why this matters for the appeal itself
Proper service of the notice of appeal is not a mere formality — it puts the other side on record notice that the case is moving to a higher court. Using an unauthorized method of service, instead of registered mail or substituted service under Rule 13, risks a defect that the adverse party could later raise. A defect in service does not necessarily void the appeal outright, but it invites the adverse party to challenge whether they were properly and timely informed that the case is going up, which can distract from the merits and delay proceedings. Following Rule 13's registered mail or substituted service procedures instead of an improvised method also creates a clear paper trail — a registry receipt or a substituted-service return — that later proves service actually happened, which matters if the adverse party denies ever receiving the notice.