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You send an email campaign to thousands of customers, but some messages bounce, others land in spam, and many never reach the inbox.
This is an email deliverability problem.
For Indian businesses, improving email deliverability requires more than choosing an email marketing platform. It involves maintaining clean contact lists, authenticating your domain, protecting sender reputation and monitoring delivery failures.
Here's how to identify common problems and fix them.
Email deliverability is whether your message reaches the inbox instead of spam. Delivery only means the receiving server accepted it. Fix problems by cleaning your list, authenticating your domain with SPF, DKIM and DMARC, building volume gradually and reading bounce responses after every campaign.
- Bounce rate is bounced emails divided by emails sent, times 100. If 200 of 10,000 emails bounce, the rate is 2%.
- A hard bounce is permanent, such as an invalid address, so stop sending to it. A soft bounce is temporary and needs investigating if it repeats.
- Google recommends a user-reported spam rate below 0.1% and never reaching 0.3%. Yahoo asks senders to stay below 0.3%.
- Bounce thresholds are provider-specific. Amazon SES, for example, places an account under review at a 5% hard-bounce rate.
- TRAI's DLT framework applies to commercial SMS, not email.
What is email deliverability?
Email deliverability refers to the ability of your emails to reach recipients' inboxes instead of being rejected or filtered into spam.
It is different from email delivery:
- Email delivery: The recipient's mail server accepts your message.
- Email deliverability: Your message reaches the intended inbox rather than being filtered into spam or another folder.
An email can be successfully delivered to a mail server but still land in the spam folder.
What is an email bounce rate?
A bounce happens when an email cannot be delivered to its intended recipient.
Bounce rate = (Bounced emails ÷ Emails sent) × 100
For example, if you send 10,000 emails and 200 bounce, your bounce rate is 2%.
There are two common types:
| Bounce type | Meaning | Example |
|---|---|---|
| Hard bounce | Permanent delivery failure | Invalid email address |
| Soft bounce | Temporary delivery failure | Full mailbox or temporary server issue |
A hard bounce usually means you should stop sending to that address. A soft bounce may resolve itself, depending on the reason.
Always check the actual bounce response or error code from your email service provider. A temporary server issue, mailbox restriction and invalid address require different actions.
Why are emails bouncing or landing in spam?
Common reasons include:
- Invalid email addresses: Old, mistyped or inactive addresses can generate hard bounces.
- Missing authentication: Incorrect SPF, DKIM or DMARC configuration can affect how receiving providers verify your emails.
- Poor sender reputation: Frequent spam complaints, repeated bounces and inconsistent sending practices can affect your domain or IP reputation.
- Sudden increases in volume: Sending large campaigns from a new or inactive domain can trigger additional scrutiny.
- Irrelevant content: When recipients regularly report your messages as spam, future campaigns may face deliverability problems.
- Technical errors: Incorrect DNS records, sender configuration and email formatting can also cause failures.
How to fix email deliverability problems
Clean your email list
- Remove addresses that have hard-bounced.
- Correct formatting errors.
- Avoid purchased or scraped lists.
- Review inactive subscribers.
- Use appropriate signup verification.
- Do not repeatedly send to addresses that have generated permanent failures.
Configure SPF, DKIM and DMARC
These authentication methods help receiving providers verify your sending domain.
| Authentication | Purpose |
|---|---|
| SPF | Identifies authorised sending servers |
| DKIM | Adds a digital signature to verify the message |
| DMARC | Defines how receiving providers handle authentication failures and provides reporting |
Configure these DNS records using the instructions from your email service provider. Check that your sending domain is correctly aligned with your authentication setup.
Google recommends starting DMARC with a p=none policy, which delivers messages as normal and records results in reports.
Build sender reputation gradually
If you're using a new domain or IP address, avoid sending a large campaign immediately.
Start with a smaller group of recipients who are likely to engage. Increase sending volume gradually while monitoring bounces and complaints.
This process is commonly called email warm-up.
Improve content and relevance
- Use a recognisable sender name.
- Write subject lines that match the actual message.
- Send relevant content to the right audience.
- Avoid misleading offers.
- Include a clear unsubscribe option in marketing emails.
Monitor failures
Review bounce reports after every campaign. Identify whether failures are related to a particular recipient domain, contact source or sending configuration.
Suppress hard-bounced addresses and investigate repeated soft bounces before attempting further sends.
Email deliverability checks for Indian businesses
Indian businesses sending campaigns to Gmail, Yahoo and Outlook recipients must consider the requirements of the receiving email providers. Their authentication and filtering systems may differ.
Before launching campaigns, check:
- Domain authentication: Verify SPF, DKIM and DMARC.
- DNS configuration: Ensure records are published correctly.
- Sending infrastructure: Understand shared or dedicated IP arrangements and reputation monitoring.
- Contact permissions: Send marketing emails to appropriately subscribed recipients.
- Unsubscribe handling: Process marketing unsubscribes promptly.
- Delivery monitoring: Review bounce and spam complaint reports.
Google requires SPF or DKIM authentication for all senders to Gmail. Bulk senders sending more than 5,000 messages per day to Gmail accounts must meet additional requirements, including SPF, DKIM and DMARC.
Google recommends keeping reported spam rates below 0.1% and avoiding rates of 0.3% or higher. Yahoo also expects bulk senders to keep complaint rates below 0.3%. These are provider-specific requirements and recommendations, not universal benchmarks.
Microsoft has also published requirements for high-volume senders to Outlook.com. Check them if you send at that volume.
For Indian businesses, remember that TRAI's DLT framework applies to commercial SMS, not email. Email authentication and telecom messaging compliance are separate requirements.
References: Google Email Sender Guidelines · Yahoo Sender Best Practices · TRAI
What should you monitor?
Email deliverability needs regular monitoring, not just occasional checks.
| Metric | What it tells you |
|---|---|
| Delivery rate | Emails accepted by receiving servers |
| Hard bounce rate | Permanent delivery failures |
| Soft bounce rate | Temporary delivery failures |
| Spam complaint rate | Recipients reporting emails as unwanted |
| Inbox placement | Whether emails reach inboxes or spam |
| Unsubscribe rate | Recipients opting out of marketing emails |
A high bounce rate does not always have the same cause. Check the actual error response and your provider's reporting before deciding what to fix.
Provider thresholds vary. Amazon SES counts only hard bounces, recommends staying below 5% and places an account under review at 5% or higher. That is an SES policy, not an industry standard. Google Postmaster Tools shows spam rate, authentication and delivery errors for mail sent to Gmail.
For example, Amazon SES documentation explains how permanent and temporary bounces differ and how they affect sending practices.
Managing email alongside other communication channels
Email is useful for newsletters, product announcements and detailed customer communication. WhatsApp and SMS can support other types of customer updates when appropriate.
Helo.ai offers email as part of its wider communication platform, alongside WhatsApp, SMS, RCS and Voice. Helo Inbound lets teams manage conversations across SMS, WhatsApp and email from a single platform.
Want to explore a more connected customer communication setup?
Talk to the Helo.ai team about how your channels fit together.
Frequently asked questions
What is a good email bounce rate?
There is no universal benchmark for every provider or sending programme. Monitor hard bounces separately and investigate sudden increases.
What is the difference between a hard bounce and a soft bounce?
A hard bounce is a permanent failure, such as an invalid address. A soft bounce is generally temporary, such as a full mailbox or server issue.
How can I improve email deliverability?
Maintain a clean, permission-based list, configure SPF, DKIM and DMARC, send relevant content and monitor complaints.
Why are my emails going to spam?
Possible reasons include poor sender reputation, authentication failures, high complaint rates or technical configuration issues.
Does changing my email service provider fix deliverability?
Not necessarily. If the underlying problem is poor list quality, domain authentication or sending practices, changing providers alone may not solve it.
What spam complaint rate is too high?
Google recommends keeping the user-reported spam rate below 0.1% and never letting it reach 0.3%. Yahoo asks senders to keep it below 0.3%.
Should I remove soft-bounced addresses immediately?
Not necessarily. A soft bounce is temporary, such as a full mailbox. Investigate repeated soft bounces before sending again, and remove addresses that hard-bounce.
Final takeaway
Good email deliverability starts before a campaign is sent. Clean contact lists, proper authentication and consistent sending practices help businesses build a reliable email programme.
Monitor bounce rates, understand why messages fail and fix the underlying issue instead of repeatedly sending to the same addresses.
Sending email alongside WhatsApp and SMS?
Explore Helo.ai email and Helo Inbound to manage email with your other channels.
Disclaimer. This article is general information, not legal or technical advice. Provider requirements, thresholds and policies change, so confirm current rules with Google, Yahoo, Microsoft and your email provider. Reviewed 12 November 2026. Helo.ai is the publisher and offers email and messaging products. Product and company names belong to their owners.
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