10 Email Deliverability Tips to Land in the Inbox, Not Spam

Deliverability is the difference between a campaign that converts and one that quietly disappears into the spam folder. These are the ten things every Bangladesh marketer running email through their own SMTP should check, in order of impact.

1. Set up SPF

An SPF TXT record tells inbox providers which servers are allowed to send mail for your domain. For Amazon SES it looks like v=spf1 include:amazonses.com ~all. Without it, almost everything goes to spam.

2. Set up DKIM

DKIM cryptographically signs every outgoing email so the recipient can verify it really came from you. Every serious SMTP provider — Gmail Workspace, SES, Mailgun, SendGrid — gives you DKIM CNAMEs to add to DNS. Add them.

3. Add DMARC

DMARC tells inbox providers what to do when SPF or DKIM fails. Start with v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com to monitor, then move to p=quarantine and finally p=reject once you are confident.

4. Send from a real subdomain

Use mail.yourdomain.com or news.yourdomain.com for marketing email. This isolates your marketing reputation from your transactional and corporate email.

5. Warm up new IPs and domains slowly

Sending 100,000 emails on day one from a brand new domain is the fastest way to get blocked. Start with 200/day, double every few days, and watch your bounce rate.

6. Keep your list clean

• Never buy lists.
• Use double opt-in.
• Remove hard bounces immediately — RAPID SMTP does this automatically.
• Re-engage or remove subscribers who have not opened anything in 6+ months.

7. Honor unsubscribes — instantly

Every campaign needs a visible one-click unsubscribe link. Gmail and Yahoo's 2024 sender requirements make this mandatory for any bulk sender. RAPID SMTP injects compliant unsubscribe links and headers automatically.

8. Throttle your sends

Blasting 50,000 emails in 60 seconds looks like spam to inbox filters and can trip your SMTP provider's rate limit. Spread the send across hours. Set the throttle on your campaign in RAPID SMTP.

9. Watch your content

• Avoid spam-trigger phrases like "FREE!!!", "100% guaranteed", "ACT NOW".
• Keep a healthy text-to-image ratio — never send an image-only email.
• Always include a plain-text version (RAPID SMTP generates this for you).

10. Monitor and iterate

Use open and click tracking to spot patterns. If a specific domain (like outlook.com) starts dropping your open rate, investigate before the problem spreads.

The TL;DR checklist

SPF + DKIM + DMARC + clean list + throttled send + working unsubscribes = inbox. Skip any one and you are gambling with your reputation. Want the platform that does most of this automatically? Try RAPID SMTP free.