Linux-Server-Management-Toolkit/modules/email/deliverability-test.sh

#!/bin/bash

################################################################################
# Email Deliverability Test - Comprehensive Email Sending Validation
################################################################################
# Purpose: Test email deliverability with authentication checks and blacklist detection
# Validates SPF/DKIM/DMARC, tests SMTP connection, checks blacklists
################################################################################

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
source "$SCRIPT_DIR/lib/common-functions.sh"
source "$SCRIPT_DIR/lib/system-detect.sh"
source "$SCRIPT_DIR/lib/email-functions.sh"

show_banner "Email Deliverability Test"

# Get input from user
echo ""
read -p "Enter domain to test (e.g., example.com): " TARGET_DOMAIN
if [ -z "$TARGET_DOMAIN" ]; then
    print_error "Domain required"
    exit 1
fi

read -p "Enter test recipient email (will receive test email): " TEST_EMAIL
if [ -z "$TEST_EMAIL" ]; then
    print_error "Recipient email required"
    exit 1
fi

read -p "Enter sender email address (e.g., test@$TARGET_DOMAIN): " SENDER_EMAIL
if [ -z "$SENDER_EMAIL" ]; then
    SENDER_EMAIL="test@$TARGET_DOMAIN"
fi

print_info "Starting comprehensive deliverability test..."
echo ""

################################################################################
# Test 1: Authentication Records Check
################################################################################

print_header "Step 1: Email Authentication Records"
echo ""

# SPF Check
print_info "Checking SPF record..."
spf_record=$(dig +short TXT "$TARGET_DOMAIN" 2>/dev/null | grep "^\"v=spf1" | sed 's/"//g')
if [ -n "$spf_record" ]; then
    print_success "  ✓ SPF record found"
else
    print_warning "  ⚠ SPF record not found (may affect deliverability)"
fi
echo ""

# DKIM Check
print_info "Checking DKIM record..."
for sel in default k1 k2 google selector1 selector2; do
    dkim_record=$(dig +short TXT "${sel}._domainkey.${TARGET_DOMAIN}" 2>/dev/null | grep "^\"v=DKIM1")
    if [ -n "$dkim_record" ]; then
        print_success "  ✓ DKIM record found (selector: $sel)"
        break
    fi
done
if [ -z "$dkim_record" ]; then
    print_warning "  ⚠ DKIM record not found (recommend enabling for better deliverability)"
fi
echo ""

# DMARC Check
print_info "Checking DMARC record..."
dmarc_record=$(dig +short TXT "_dmarc.${TARGET_DOMAIN}" 2>/dev/null | grep "^\"v=DMARC1" | sed 's/"//g')
if [ -n "$dmarc_record" ]; then
    print_success "  ✓ DMARC record found"
else
    print_warning "  ⚠ DMARC record not found (recommended for authentication monitoring)"
fi
echo ""

################################################################################
# Test 2: SMTP Connection Test
################################################################################

print_header "Step 2: SMTP Connection Test"
echo ""

print_info "Testing SMTP connectivity..."

# Get MX records
MX_RECORDS=$(dig +short MX "$TARGET_DOMAIN" 2>/dev/null | head -5)

if [ -z "$MX_RECORDS" ]; then
    print_error "  ✗ No MX records found for $TARGET_DOMAIN"
    echo "    Cannot test SMTP connectivity"
else
    print_success "  ✓ MX records found:"
    while read priority server; do
        server=$(echo "$server" | sed 's/\.$//')
        echo "    • Priority $priority: $server"

        # Try to connect to SMTP using multiple methods
        local smtp_ok=0

        # Try nc first if available
        if command -v nc &>/dev/null; then
            if timeout 3 bash -c "echo 'QUIT' | nc -z -w 1 \"$server\" 25" &>/dev/null; then
                smtp_ok=1
            fi
        fi

        # Try timeout with bash TCP if nc not available
        if [ $smtp_ok -eq 0 ] && timeout 3 bash -c "exec 3<>/dev/tcp/$server/25 && echo QUIT >&3 && cat <&3" &>/dev/null; then
            smtp_ok=1
        fi

        if [ $smtp_ok -eq 1 ]; then
            print_success "      ✓ SMTP port 25 responds"
        else
            print_warning "      ⚠ SMTP port 25 not responding (may use port 587/465)"
        fi
    done < <(echo "$MX_RECORDS")
fi
echo ""

################################################################################
# Test 3: Blacklist Check (from email-diagnostics)
################################################################################

print_header "Step 3: Server IP Blacklist Check"
echo ""

# Get server's public IP
print_info "Detecting server IP address..."
SERVER_IP=$(curl -s --max-time 5 ifconfig.me 2>/dev/null || curl -s --max-time 5 icanhazip.com 2>/dev/null || echo "")

if [ -z "$SERVER_IP" ]; then
    print_warning "  ⚠ Could not detect server IP (skipping blacklist check)"
else
    print_success "  Server IP: $SERVER_IP"
    echo ""

    # Check major blacklists
    BLACKLISTS_DB=(
        "zen.spamhaus.org|Spamhaus"
        "bl.spamcop.net|SpamCop"
        "bl.barracudacentral.org|Barracuda"
        "dnsbl.sorbs.net|SORBS"
        "cbl.abuseat.org|CBL"
    )

    print_info "Checking major blacklists..."
    REVERSED_IP=$(echo $SERVER_IP | awk -F. '{print $4"."$3"."$2"."$1}')

    listed=0
    for entry in "${BLACKLISTS_DB[@]}"; do
        IFS='|' read -r rbl_host rbl_name <<< "$entry"

        if dig +short +timeout=2 "${REVERSED_IP}.${rbl_host}" A 2>/dev/null | grep -q .; then
            print_error "    ✗ $rbl_name: LISTED (may cause delivery issues)"
            ((listed++))
        else
            print_success "    ✓ $rbl_name: Not listed"
        fi
    done

    if [ $listed -gt 0 ]; then
        echo ""
        print_warning "  ⚠ Your IP is listed on $listed blacklist(s)"
        echo "    Recommendation: Use blacklist-check tool for delisting options"
    fi
fi
echo ""

################################################################################
# Test 4: Reverse DNS Check
################################################################################

print_header "Step 4: Reverse DNS (PTR Record) Check"
echo ""

print_info "Checking reverse DNS..."
if [ -n "$SERVER_IP" ]; then
    PTR_RECORD=$(dig +short -x "$SERVER_IP" 2>/dev/null)
    if [ -n "$PTR_RECORD" ]; then
        print_success "  ✓ PTR record found: $PTR_RECORD"
        echo "    Reverse DNS is properly configured"
    else
        print_error "  ✗ PTR record not found"
        echo "    Recommendation: Contact your hosting provider to set reverse DNS"
    fi
else
    print_warning "  ⚠ Could not determine server IP (skip PTR check)"
fi
echo ""

################################################################################
# Test 5: Send Test Email
################################################################################

print_header "Step 5: Send Test Email"
echo ""

print_info "Composing and sending test email..."

# Create test email
TEST_EMAIL_FILE="/tmp/deliverability_test_$$.txt"
cat > "$TEST_EMAIL_FILE" << EMAILEOF
Subject: Email Deliverability Test from $TARGET_DOMAIN
From: $SENDER_EMAIL
To: $TEST_EMAIL
Date: $(date -R)

This is an automated email deliverability test from:
Domain: $TARGET_DOMAIN
Server IP: ${SERVER_IP:-Unknown}
Timestamp: $(date)

If you received this email, your email system is working correctly.

Check the email headers to verify:
- SPF authentication result
- DKIM signature
- DMARC alignment

---
Sent from Email Deliverability Test Tool
EMAILEOF

# Try to send email
if command -v sendmail &> /dev/null; then
    if sendmail "$TEST_EMAIL" < "$TEST_EMAIL_FILE" 2>/dev/null; then
        print_success "  ✓ Test email sent successfully via sendmail"
        echo "    Recipient should receive email at: $TEST_EMAIL"
    else
        print_warning "  ⚠ sendmail submission may have failed"
    fi
elif command -v mail &> /dev/null; then
    if echo "" | mail -s "Email Deliverability Test" -r "$SENDER_EMAIL" "$TEST_EMAIL" 2>/dev/null; then
        print_success "  ✓ Test email sent successfully via mail command"
        echo "    Recipient should receive email at: $TEST_EMAIL"
    else
        print_warning "  ⚠ mail command submission may have failed"
    fi
else
    print_warning "  ⚠ No mail sending utility found (sendmail/mail)"
    echo "    Email sending cannot be tested on this system"
fi

rm -f "$TEST_EMAIL_FILE"
echo ""

################################################################################
# Test Summary & Recommendations
################################################################################

print_header "Deliverability Test Summary"
echo ""

echo "📧 Test Configuration:"
echo "  Domain: $TARGET_DOMAIN"
echo "  Sender: $SENDER_EMAIL"
echo "  Recipient: $TEST_EMAIL"
if [ -n "$SERVER_IP" ]; then
    echo "  Server IP: $SERVER_IP"
fi
echo ""

echo "✅ Recommended Next Steps:"
echo ""
echo "1. Check recipient inbox for test email"
echo "   Look for the email from $SENDER_EMAIL"
echo ""
echo "2. Review email headers:"
echo "   - Verify 'Authentication-Results' header"
echo "   - Check SPF, DKIM, DMARC results"
echo "   - Look for any 'pass' or 'fail' indications"
echo ""
echo "3. If email didn't arrive:"
echo "   - Check spam/junk folder"
echo "   - Review mail server logs: tail -f /var/log/mail.log"
echo "   - Use email-diagnostics tool: email-diagnostics"
echo "   - Check blacklist status: blacklist-check"
echo ""
echo "4. For authentication issues:"
echo "   - Validate records: spf-dkim-dmarc-check"
echo "   - Analyze mail logs: mail-log-analyzer"
echo ""

echo "🔗 Related Tools:"
echo "  • email-diagnostics  - Analyze specific email delivery issues"
echo "  • blacklist-check    - Check IP reputation on RBLs"
echo "  • spf-dkim-dmarc-check - Validate authentication records"
echo "  • mail-log-analyzer  - Analyze mail server logs"
echo ""