Running your own SMTP server for email delivery, especially to major providers like Microsoft (Hotmail/Outlook), presents unique challenges that go beyond basic server configuration. The issue isn't just about technical setup, but also about reputation management in an ecosystem dominated by large email service providers.

Let's verify your current setup meets all technical requirements:

# Sample DNS records verification
dig TXT buildoneforme.com  # Check SPF
dig TXT _dmarc.buildoneforme.com  # Check DMARC
dig MX buildoneforme.com  # Check MX records
dig -x 144.76.81.247  # Verify reverse DNS

Microsoft's filtering algorithms are particularly aggressive against smaller IP ranges. Even with perfect configuration, new IPs need to build reputation gradually. Their JMRP and SNDS programs are good starts, but insufficient alone.

Using your top-level domain for mailserver identification isn't technically wrong, but violates common conventions. Consider this postfix configuration adjustment:

# In /etc/postfix/main.cf
myhostname = mail.buildoneforme.com
smtpd_banner = $myhostname ESMTP $mail_name

Instead of creating fake accounts (which violates terms of service), try these legitimate methods:

• Send regular (not bulk) emails to real contacts who can whitelist you
• Maintain consistent sending patterns (don't spike suddenly)
• Ensure high engagement from recipients

For mission-critical email (like your mailing list), hybrid approaches often work best:

// Example using Amazon SES with Postfix as relay
# In /etc/postfix/main.cf
relayhost = [email-smtp.us-west-2.amazonaws.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_security_level = encrypt

Implement comprehensive logging and monitoring:

# Sample exim4 log parser for bounce rates
grep "r=dkim" /var/log/exim4/mainlog | awk '{print $6}' | sort | uniq -c
# Monitor Microsoft-specific bounces
grep "hotmail\\|outlook" /var/log/exim4/mainlog | grep "rejected"

While technically possible to maintain good deliverability with self-hosted solutions, the operational overhead is significant. For mailing lists especially, using a specialized service (Mailchimp, SendGrid, etc.) often proves more effective in the long run.

Running your own SMTP server for email delivery has become increasingly challenging with modern spam filters. Microsoft's filtering algorithms (used by Outlook/Hotmail) are particularly aggressive against small-scale senders. Here's a deep dive into why your carefully configured setup might still hit junk folders.

Your implementation checks most standard boxes:

# Sample SPF record configuration
"v=spf1 a mx ip4:144.76.81.247 -all"

# Example DKIM setup in Exim4
dkim_selector = "default"
dkim_private_key = "/etc/exim4/dkim.private.key"
dkim_domain = "buildoneforme.com"

Yet Microsoft still applies the "small sender penalty" - their filters automatically distrust IPs with low sending volume. This is the hidden challenge the big email providers won't explicitly tell you about.

While using buildoneforme.com directly instead of mail.buildoneforme.com isn't technically wrong, it does raise some eyebrows at filtering systems. Here's how to modify your Exim4 configuration:

# In exim4.conf.template
primary_hostname = mail.buildoneforme.com
helo_data = mail.buildoneforme.com

They won't admit it, but Microsoft expects new IPs to follow an invisible warm-up protocol:

• Start with 10-20 messages per day to Microsoft recipients
• Gradually increase volume over 4-6 weeks
• Maintain consistent sending patterns (no spikes)

Beyond basic SPF/DKIM, try these Exim4 optimizations:

# Add these to your exim4.conf
smtp_active_hostname = mail.buildoneforme.com
tls_on_connect_ports = 465
smtp_banner = mail.buildoneforme.com ESMTP Exim $version_number

For a mailing list with hundreds of members, you're approaching the threshold where maintaining your own deliverability becomes impractical. Services like Amazon SES offer:

• Pre-warmed IP pools
• Built-in reputation monitoring
• Automatic bounce handling

Here's a quick SES integration example:

# Python example using boto3
import boto3
client = boto3.client('ses')
response = client.send_email(
    Source='newsletter@yourdomain.com',
    Destination={'ToAddresses': ['user@example.com']},
    Message={...}
)

Instead of creating fake accounts, use these professional tools:

• Microsoft's SAR (Sender/Receiver) test accounts
• Google Postmaster Tools
• MXToolbox Blacklist Check

For personal email, persistent configuration tuning can work. For mailing lists, third-party services will save countless hours fighting deliverability battles. The choice ultimately depends on how much time you want to spend on infrastructure versus running your community.