#!/bin/bash
set -o errexit
set -o nounset
set -o pipefail
shopt -s lastpipe
function join_by {
local d=${1-} f=${2-}
if shift 2; then
printf %s "$f" "${@/#/$d}"
fi
}
results=$(mktemp)
cleanup() {
rm "$results"
}
trap cleanup SIGINT SIGHUP SIGABRT EXIT
declare -a addresses
while read -r key _; do
addresses+=("${key%:*}")
done </etc/exim4/otrs_emails
grep -E '=> ('"$(join_by '|' "${addresses[@]}")"')' < <(zcat /var/log/exim4/mainlog.*.gz) >"$results"
declare -Ai domain_names
declare -Ai local_names
for email in "${addresses[@]}"; do
count=$(grep -c '=> '"$email" <"$results") || true
IFS='@' read -r local_name domain_name <<<"$email"
local_names[$local_name]+=$count
domain_names[$domain_name]+=$count
done
printf '\nTop Local Names:\n'
for local_name in "${!local_names[@]}"; do
printf '%d\t%s\n' "${local_names[$local_name]}" "$local_name"
done | sort -n | tail -n 20
printf '\nTop Domain Names:\n'
for domain_name in "${!domain_names[@]}"; do
printf '%d\t%s\n' "${domain_names[$domain_name]}" "$domain_name"
done | sort -n | tail -n 20