皆さん、大変ご無沙汰しております。I remember a year or two ago, there was a thread about writing a letter/email to someone you don't know. This never happens in regular Japanese society (there's always an intermediary), but it does occur sometimes in international communications. I haven't been able to dig up the thread with the search function, so I'm hoping someone here has it bookmarked, or at least knows of a similar resource. Any help would be appreciated.

This?
I also found a much older thread about writing to someone whose name you don't know: here

That's exactly the thread I was looking for! Thank you, Vempele.

This may be another way of putting it:
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突然のメールをどうかお許しください。
まったく知らない人間からのこのようなメールにさぞかし驚かれていらっしゃることとお察しいたします。
私はcountryの○○大学で○○・○○学を専攻している、○○と申します。
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And I would also google stuff using keywords like those for example:
- ビジネスメール+敬語+例　
- ビジネスメールの書き方　
- 知らない人にメールを送る + ビジネス