Keep your emails out of spam

A login code that arrives in spam, or two minutes late, is a lost user. Most delivery problems come from a short list of causes. Work through them in this order.

1. Authenticate your domain

Unauthenticated email is the most common reason for the spam folder. Verify your domain so every email is DKIM-signed and SPF-aligned, then add a DMARC record. SPF, DKIM and DMARC explained covers what each one does.

2. Send from a subdomain

Send product email from a subdomain such as mail.acme.in or notify.acme.in instead of acme.in. Mailbox providers track reputation per domain, so a mistake in one stream won’t hurt the other, and your team’s normal office email stays unaffected.

3. Look like the same sender every time

• Use one recognisable From name and address, for example Acme <[email protected]>.
• Prefer an address people can reply to. If you must use no-reply@, say where to get help.
• Keep the subject plain and specific: Your Acme login code is 482913 beats Important!!!.

4. Keep the email simple

• Always send a text version alongside the HTML. Vaartix accepts both in one call.
• Use a few links, all on your own domain. Avoid URL shorteners such as bit.ly; spammers use them heavily.
• Don’t build the email from one large image. Filters can’t read images, and many inboxes block them.
• Keep the HTML light: no scripts, forms or embedded videos.

5. Only email people who asked

• Send transactional email only to addresses that signed up or bought something.
• Never retry addresses that bounced. Vaartix suppresses hard bounces and complaints automatically; check GET /emails/{id} to see why an email was skipped.
• Remove signups that never confirmed their address.

6. Stop OTP abuse

Bots sometimes use sign-up and login forms to send thousands of codes to addresses they don’t own. The bounces and complaints that follow damage your reputation fast, and Vaartix pauses accounts whose bounce rate passes 4% or complaint rate passes 0.08%.

• Add a CAPTCHA (such as Cloudflare Turnstile or reCAPTCHA) to forms that send codes.
• Limit codes per address and per IP address, for example 5 per hour.
• Only send a code to an existing account’s address on login, not to any address typed in.

7. Grow volume gradually

A new domain that suddenly sends 50,000 emails looks suspicious. Start with your real traffic and let volume grow over a few weeks. Daily limits on new Vaartix accounts follow the same idea.

8. Watch the signals

• Gmail Postmaster Tools (free): add your domain to see your reputation and spam rate at Gmail, which handles most personal email in India.
• Bounce and complaint rates: list recent emails with GET /emails and watch for bounced and complained statuses.
• mail-tester.com: send a test email to the address it gives you for a quick score and fixes.

Testing without hurting your reputation

Use test mode while developing. Emails to delivered@, bounced@ and [email protected] produce real events without sending anything, so your tests never count against your reputation.