In most states, landlords may deliver an eviction notice by hand, through the mail with proof of service, or through an electronic communication such as email (if the tenant agreed in writing to receive notices this way).
However, some states and territories (such as the Australian Capital Territory) require police to carry out evictions. As such, it's important to consult your local landlord and tenant authority before proceeding with an eviction.
If you deliver the document in person, having an objective third party witness the event is beneficial if the tenant ever denies receiving the notice.
If you send the notice through the mail, it's generally advisable to send it through a registered post service. This kind of mail service provides proof of delivery and receipt (often with a signature on delivery and online tracking). Sending a notice through a registered post service often provides more security than sending it electronically.
If you serve the notice through email, you can check if your email service allows you to request delivery and read receipts. A delivery receipt confirms the delivery of your email to the recipient's mailbox, while a read receipt confirms the email was opened.
Unfortunately, not all email services support read receipts, and there is no way to force a recipient to send a read receipt. Notedly, serving an eviction notice via email is often difficult to prove in court, and Australian law makers have only recently ruled emails as a valid form of communication.