Email Deliverability

Inbox Placement = Authentication + Reputation + Content + Engagement

Authentication: SPF, DKIM, DMARC properly configured
Reputation: Sender history, complaint rates, bounces
Content: Not spammy, proper formatting, good practices
Engagement: Opens, clicks, replies from recipients

What it does:
├── Lists authorized servers for your domain
├── Receiving servers check if sender is allowed
├── Prevents spoofing from unauthorized servers

DNS Record Example:
v=spf1 include:_spf.google.com include:sendgrid.net ~all

Components:
├── v=spf1: Version identifier
├── include: Authorized sending services
├── ~all: Soft fail for unauthorized (recommended)
├── -all: Hard fail (stricter)

What it does:
├── Adds cryptographic signature to emails
├── Proves email wasn't modified in transit
├── Links email to your domain

Setup:
1. Generate key pair in email platform
2. Add public key to DNS as TXT record
3. Platform signs outgoing emails
4. Receivers verify signature

DNS Record Example:
selector._domainkey.yourdomain.com
v=DKIM1; k=rsa; p=MIGfMA0GCSqG...

What it does:
├── Tells receivers what to do with failed auth
├── Provides reporting on authentication results
├── Protects your domain from spoofing

Policies:
├── p=none: Monitor only (start here)
├── p=quarantine: Send to spam if fails
├── p=reject: Block if fails (strongest)

DNS Record Example:
_dmarc.yourdomain.com
v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com; pct=100

For DMARC to pass, either SPF OR DKIM must align:

SPF Alignment:
├── Return-Path domain matches From domain
└── Or shares same organizational domain

DKIM Alignment:
├── DKIM signing domain matches From domain
└── Or shares same organizational domain

Best Practice: Ensure BOTH align for maximum deliverability

IP Reputation:
├── Shared IP: Affected by other senders
├── Dedicated IP: Only your sending history
└── New IPs need warming period

Domain Reputation:
├── Your sending domain history
├── More important than IP in 2025
├── Takes longer to repair if damaged

Tools:
├── Google Postmaster Tools (Gmail)
├── Microsoft SNDS (Outlook/Hotmail)
├── Yahoo Sender Hub
├── MXToolbox (blacklists)
├── Sender Score (Validity)

What to monitor:
├── Domain reputation score
├── Spam complaint rate
├── Authentication pass rate
├── IP reputation

All Senders Must:
├── Set up SPF or DKIM authentication
├── Have valid PTR records (reverse DNS)
├── Use TLS for transmission
├── Keep spam complaints under 0.3%
├── Follow RFC 5322 message format

Bulk Senders (5,000+ emails/day) Must Also:
├── Set up DMARC (p=none minimum)
├── Have SPF AND DKIM alignment
├── Include one-click unsubscribe header
├── Honor unsubscribes within 2 days

New Microsoft Requirements:
├── DMARC required for bulk senders
├── Applies to Outlook.com, Hotmail, Live.com
├── Non-compliant emails may be rejected
├── Similar to Gmail/Yahoo requirements

Required Header:
List-Unsubscribe: <mailto:unsubscribe@domain.com>,
  <https://domain.com/unsubscribe?id=123>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

Benefits:
├── Required for bulk senders
├── Reduces spam complaints
├── Better user experience
├── Most ESPs handle automatically

Step 1: Check authentication
└── Use mail-tester.com or MXToolbox

Step 2: Check reputation
└── Google Postmaster, Sender Score

Step 3: Check content
└── SpamAssassin score, link reputation

Step 4: Check list quality
└── Bounce rates, engagement rates

For Spam Folder Issues:
├── Verify all authentication
├── Remove unengaged subscribers
├── Reduce sending volume temporarily
├── Request whitelist from engaged users

For Blacklist Removal:
├── Identify which blacklist
├── Fix the underlying issue
├── Submit removal request
├── Wait for de-listing (24-72 hours)

Regular Cleaning:
├── Remove hard bounces immediately
├── Remove 3+ month unengaged
├── Suppress complainers permanently
├── Verify new signups (double opt-in)

Sunset Policy:
├── 90 days no opens → reduce frequency
├── 180 days no opens → re-engagement campaign
├── 270 days no opens → remove from list

For New IPs/Domains:
Week 1: 50-100 emails/day
Week 2: 200-500 emails/day
Week 3: 1,000-2,000 emails/day
Week 4: 5,000-10,000 emails/day

Tips:
├── Start with most engaged subscribers
├── Monitor closely for issues
├── Slow down if problems arise
├── Takes 4-8 weeks typically

Avoid Spam Triggers:
├── ALL CAPS in subject lines
├── Excessive punctuation!!!
├── "Free", "Act Now", "Limited Time"
├── Image-only emails
├── URL shorteners
├── Too many links

Include:
├── Clear sender name
├── Physical mailing address
├── Easy unsubscribe link
├── Text and HTML versions