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In the UK, I have noticed that on envelopes, the text preceding the return address has changed from "If undeliverable, please return to:" to "If undelivered, please return to:".

To me, the term "undeliverable" seems more logical. Something is always "undelivered" until it has been delivered, so the "undelivered" form almost suggests that no attempt need be made at delivering it before returning it.

Therefore, I'm interesting in knowing the perceived advantages and disadvantages of each phrasing, and any suggestions as to why "undelivered" seems to be the norm these days.

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Wouldn't undeliverable mean that it couldn't be delivered anywhere, like even the post office? – user3306356 Mar 23 '14 at 11:24
up vote 1 down vote accepted

Undeliverable referes to the impossibility of being delivered: such cases as wrong address of unavailable receiver ( dead or missing). Undelivered refers to attempts being made unsuccessfully, like in the cases where you need to sign to receive an envelope or parcel.

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Thanks. This seems to support my preference for using undeliverable, because one would expect the mail service to reattempt delivery if no-one was available to sign on the first attempt, rather than to immediately return it to the sender. Also these terms are used when no signature is required and when the letter/parcel easily fits in the letterbox. – sarcadam Mar 23 '14 at 11:52
Sometimes mail can be undelivered because the addressee refuses to accept it. Personally I reject all unsolicited advertising (junk mail), returning it to the sender, at their expense. Normally I do this by writing 'Return to Sender' on the envelope and re-posting it in a letter box. The mail in question was 'deliverable' but was 'undelivered' because the recipient refused to accept it. – WS2 Mar 23 '14 at 12:42
@WS2: Thanks. Perhaps neither 'deliverable' nor 'delivered' are wholly appropriate, and it's just a matter of selecting a short term that is widely understood even if not entirely accurate. One could argue that your mail had been delivered prior to you returning it via the post box, but was undeliverable because you rejected it, but I would agree that being simultaneously delivered and undeliverable is not a great argument. – sarcadam Mar 23 '14 at 13:50
Undeliverable suggests that it is known that it cannot be delivered right from the outset. Undelivered means that delivery was attempted but, for whatever reason, failed. At this point, it could be determined that it "was undeliverable" or "is undeliverable", but this is not known until it is determined to have been "undelivered". – nxx Mar 23 '14 at 15:03

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