。
In about a year and a half, he sent approximately 2.2 billion spam emails.
Literal
About 1.5-years [in-で] about 2.2-billion pieces [genitive-の] spam-mail [object-を] sent.
A news-crime report. The で here is the duration/time-frame で — 'in the span of X.' Distinct from the causal/instrumental で. 約 ('about, approximately') is the news-register approximation prefix, appearing here twice. 通 (つう) is the counter for letters, emails, and other pieces of written correspondence — 1 通 (one letter/email), 2 通 (two letters/emails). 迷惑メール ('nuisance mail') is the standard Japanese term for 'spam' — 迷惑 means 'nuisance, bother,' and the compound captures the unwelcome nature of the messages. The verb 送る ('send') is one of the most basic action verbs.