Email deliverability in India: getting past spam filters and into the inbox
Sending emails is easy. Getting them into the inbox is not. Here is what actually affects deliverability for Indian senders.
Your email open rates are low. Before you blame the subject line, check whether your emails are reaching the inbox at all. Many Indian businesses discover that 20 to 40 percent of their sends land in spam or promotions tabs without anyone knowing.
Deliverability is the infrastructure layer under your email marketing. No amount of great content fixes a technical reputation problem.
What spam filters actually check
Modern spam filters like Google's and Microsoft's do not just scan for "Buy now" or suspicious links. They evaluate a combination of signals.
Sender reputation is the biggest one. Your sending IP and domain have a reputation score based on past behaviour: bounce rates, spam complaint rates, engagement rates, and whether the addresses you send to actually exist. If 5% of your list marks you as spam, your reputation drops fast.
Authentication is checked next. SPF, DKIM, and DMARC are three DNS records that prove you are actually authorised to send email from your domain. If even one of these is missing or misconfigured, many mail servers will either reject your email or route it to spam automatically. If you send from a tool like Mailchimp, Mailmodo, or SendGrid, they typically help you set these up, but many Indian businesses skip this step.
Content signals still matter but less than they used to. Long URLs, image-heavy emails with little text, and too many links can still trigger filters. A plain-text email with one link will almost always have better deliverability than an image-heavy HTML newsletter.
The Indian sender reputation problem
A specific challenge for Indian businesses is that many started email marketing using shared IP pools from cheap email tools. If other senders on those shared IPs had bad practices, your reputation inherited their problems. This is why moving to a dedicated IP or a higher-quality ESP matters as volume grows.
Bulk SMS providers in India sometimes push businesses toward mass email tools that are optimised for volume, not deliverability. These tools may have lower inbox rates than a more expensive option like Mailmodo, Klaviyo, or even Mailchimp.
Key metrics to monitor
Bounce rate: hard bounces (invalid addresses) above 2% signal a list quality problem. Soft bounces (temporary delivery failures) above 5% suggest reputation or infrastructure issues.
Spam complaint rate: Google Postmaster Tools shows your complaint rate for Gmail recipients. Keep it below 0.1%. Above 0.3% and Gmail starts routing all your mail to spam.
Open rate by domain: if your Gmail open rates are dramatically lower than Outlook or Yahoo, it suggests Gmail specifically is filtering you. Check Google Postmaster Tools and look at your domain reputation score there.
Warming up a new domain or IP
If you are starting fresh with a new sending domain, or moving to a dedicated IP, you cannot immediately send 50,000 emails. You need to warm up gradually.
Start with 200 to 500 sends per day for week one, targeting your most engaged subscribers. Increase by 50% each week. The goal is to build a history of high engagement rates before scaling volume. Gmail and Microsoft track your sending patterns and a sudden spike from a new domain reads as suspicious.
For Indian businesses sending in batches around festival seasons, plan the warmup to finish at least 4 weeks before Diwali, Holi, or the specific spike period. Trying to warm up and run a high-volume Diwali campaign simultaneously usually damages deliverability.
Frequently asked questions
What are SPF, DKIM, and DMARC and do I need all three?
SPF tells receiving servers which IP addresses are allowed to send email from your domain. DKIM adds a cryptographic signature to your emails. DMARC tells receiving servers what to do if SPF or DKIM fails. You need all three. Missing any one of them leaves a gap that spam filters penalise. Your ESP or IT team can help set these up in your domain's DNS settings, typically at your registrar like GoDaddy or Namecheap.
Why do my emails go to Gmail's Promotions tab instead of the Primary inbox?
Google's tabs are separate from spam filtering. Promotions tab placement is based on commercial email signals: HTML formatting, multiple links, unsubscribe headers, and sender patterns. To improve Primary tab placement, send more plain-text emails, reduce the number of links, and encourage engaged subscribers to move your emails to Primary manually. One-to-one-style emails from a personal-looking sender address tend to land in Primary more often.
How do I check my email deliverability before sending a large campaign?
Use tools like Mail-Tester (mail-tester.com) or MXToolbox to check your authentication setup. Set up Google Postmaster Tools for your domain to monitor your Gmail reputation. Send a test campaign to a seed list of your own email addresses across Gmail, Outlook, and Yahoo before sending to your full list.