Lauren sent 65 + 10 = <<65+10=75>>75 pieces of mail on Tuesday.
He sent 75 - 5 = <<75-5=70>>70 pieces of mail on Wednesday.
And sent 70 + 15 = <<70+15=85>>85 pieces of mail on Thursday.
Therefore, he sent 65 + 75 + 70 + 85 = <<65+75+70+85=295>>295 pieces of mail.
#### 295