Spam
Spam Mail, Junk Mail, Unsolicited Mail
noun
When you have "troublesome" (迷惑) mail, you have mail you don't want. This is known as spam, spam mail, or junk mail. On a more technical level it's unsolicited mail.
The reading comes from 迷惑, so if you know that you know this (and then this vocab word won't be unsolicited as well!)
迷惑メールが次から次へと送られてくる。
I get one spam mail after another.
最近、迷惑メールが増えて困っています。
Lately, I've been getting more spam emails, and it’s really annoying.
迷惑メールが多すぎて、受信ボックスがすぐにいっぱいになるんです。
I get so much junk mail that my inbox fills up quickly.
コウイチからのメールはいつも迷惑メールフォルダに入ってしまうんだけどどうしてなんだろう？
Emails from Koichi are always found in the junk mail folder. I wonder why.