The battered parcel was delivered to a Melbourne tennis club after it was first ordered in the mid-1970s, a media report said on Friday.
The parcel, containing sew-on patches of the club's crest, is believed to have fallen behind machinery in a sorting centre at Australia Post the state-owned mail service only to be discovered recently when the company moved to another facility, reported Xinhua citing News Corp.
Former committee member of the tennis club Irene Garrett, who the package was addressed to, said she "had a good laugh" when the item finally arrived.
"I couldn't believe it, I'd forgotten all about. We're guessing it must have been around 1975, and I must have ordered it," Garrett was quoted as saying on Friday. "I'm guessing I ordered it because it was addressed to me."
The name and address on the envelope remained legible four decades on, according to Garett.
Garrett, who is no longer associated with the tennis club, thanked Australia Post workers for its better-late-than-never attitude.
"It's allowed us to get back in touch with past members of our club and we've heard some fantastic stories about what used to happen in the early days," Garrett said.
"(The parcel) could have just been thrown in the bin but it's great that people are so honest to say we found something and to deliver it."