#!/usr/bin/env bash
set -euo pipefail

LIST="$1"
DONE="$2"
EMAIL="$3"
MAX=${4:-1}

touch "$DONE"
count=0

while IFS= read -r line; do
    grep -Fxq -- "$line" "$DONE" && continue

    if msmtp "$line" < "$EMAIL"; then
        printf '%s\n' "$line"
        printf '%s\n' "$line" >> "$DONE"
        ((++count >= MAX)) && break
    else
        echo "FAILED: $line" >&2
        grep -v $line $LIST > tmp
        mv tmp $LIST
    fi

done < "$LIST"