Short answer. The envelope must be sealed and plainly addressed to the party or counsel, with postage fully pre-paid, and it must carry instructions telling the postmaster to return the mail to you after ten calendar days if it goes undelivered. Skipping any of these particulars weakens later proof of service.

What the law says

Service by registered mail shall be made by depositing the copy in the post office, in a sealed envelope, plainly addressed to the party or to the party's counsel at his or her office, if known, otherwise at his or her residence, if known, with postage fully pre-paid, and with instructions to the postmaster to return the mail to the sender after ten calendar days if undelivered.

Rule 13, Section 7 — Service by mail. Read the full provision →

What the envelope must show

Registered mail service is not just dropping an envelope in the mailbox. The rule requires the copy to be deposited at the post office in a sealed envelope, plainly addressed to the party or, if the party is represented, to counsel at the office address if known, or otherwise at the residence if known. Postage must be fully pre-paid before the envelope leaves your hands, and the envelope must carry an instruction directing the postmaster to return the mail to the sender if it remains undelivered after ten calendar days. Skipping any of these particulars can undercut proof that service was properly attempted, since each element is something a court can later check against the registry receipt and affidavit of mailing.

Why the ten-day return instruction matters

The postmaster's return instruction is what eventually tells you, and later the court, whether the addressee actually received the mail or simply left it unclaimed. Without that instruction on the envelope, there is no formal trigger for the post office to send the item back after ten days, which in turn affects how service is proved and when it is deemed complete under the rule that follows this one. This is why the instruction is not a courtesy but a required part of the mailing procedure itself, and its absence can later be used to argue that registered mail service was never properly accomplished at all.

When ordinary mail is allowed instead

The rule carves out one exception to registered mail: if no registry service is available in the locality of either the sender or the addressee, service may be done by ordinary mail. This is a narrow allowance tied to the actual absence of registry facilities in one of those two places, not a matter of convenience or cost, so a party cannot simply choose ordinary mail because it is cheaper, faster, or more familiar. Where registry service does exist in both localities, the party serving pleadings must use it and follow the sealed-envelope, prepaid-postage, and return-instruction requirements set out above.

Keeping the paper trail

Because the addressing, postage, and return instruction are all part of what must later be proven, it is worth keeping the envelope's registry receipt and any post-office documentation showing these details were followed. That paperwork becomes the backbone of the affidavit a party must eventually submit to establish that registered mail service was properly made, and a mismatch between what the envelope actually showed and what the affidavit later claims can undermine an otherwise valid attempt at service.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.