What does 便りの空だのみ mean? is grieving for ( is his friend) who left for war a year ago: > ―――― **** 1935–1939 What does mean pronounced as in audiobook)? Is it a fixed expression? Reference: aozora.gr.jp/cards/001562/files/52396_49781.html

It should be parsed as:

> []{} + + []{}

The "key" element here is , which _**does not**_ mean "sky". It means "empty", "vain", etc.

Thus, means "hope against hope". . is a rendaku.

means "correspondence", "letter", "news", etc.

All in all, you should have something like:

> "indulging in vain hope for a letter"
>
> "hope against hope for some news"

The part could be read as well. Not sure which one was the author's intended reading.