What is the difference between ZeptoMail and Zoho Mail?

Zoho Mail is an email hosting service (like Gmail), while ZeptoMail is a dedicated transactional email service (like SendGrid or Brevo). ZeptoMail is built specifically for sending application-generated emails (like AI replies) at scale, offering better analytics, delivery speed, and domain reputation control than a standard email inbox.

Why do I need to verify my domain with SPF and DKIM records?

ZeptoMail requires domain verification to prevent email spoofing and improve deliverability. SPF and DKIM are authentication methods that prove to email providers (Gmail, Outlook, etc.) that emails sent from your domain via ZeptoMail are legitimate. This significantly reduces the chance of your AI replies landing in spam folders. The setup takes about 5-10 minutes and is a one-time task.

What is a Mail Agent in ZeptoMail?

A Mail Agent is like a 'sending profile' within ZeptoMail. It groups your SMTP credentials, sending domain, and bounce-handling settings. You can create separate Mail Agents for different purposes (e.g., one for Mail AI replies, one for newsletter). Using a dedicated Mail Agent for Mail AI helps you track usage and manage settings independently.

How many emails can I send with ZeptoMail?

ZeptoMail operates on a credit-based system. You purchase credits, which never expire, and each email sent consumes one credit. New accounts usually start with a free trial credit. This pay-as-you-go model makes it very flexible for high-volume users who don't want a monthly subscription. You can monitor your credit usage in the ZeptoMail dashboard.

Will my AI replies show as sent via ZeptoMail or Mail AI?

No. The recipient will only see your FROM email address and name. ZeptoMail acts as the infrastructure that delivers the email, similar to how a postal service delivers a letter but doesn\'t appear as the sender. The email will be properly threaded in your customer\'s inbox, looking exactly as if you sent it from your regular email client.

What is the difference between ZeptoMail and Brevo for Mail AI?

Both are excellent choices. Brevo is a great all-in-one platform with a generous free plan (300 emails/day) and is very easy to set up. ZeptoMail is ideal for high-volume users who prefer a pay-as-you-go model with no daily limits and who are already familiar with Zoho\'s ecosystem. If you\'re sending a high volume of replies (hundreds per day) or want credits that never expire, ZeptoMail is the better fit.

How to Set Up ZeptoMail SMTP for AI Email Replies in Mail AI

ZeptoMail (by Zoho) is a powerful transactional email service designed for high-volume, application-sent emails. For Mail AI users, it offers a robust and scalable way to send AI-drafted replies from your custom domain email address — like [email protected] or [email protected].

Unlike traditional email providers, ZeptoMail uses a pay-as-you-go credit system, making it cost-effective for businesses that send a high volume of replies. Setup involves verifying your domain once, and then you're ready to send thousands of emails reliably.

🟠 Why ZeptoMail is great for high-volume business replies: It offers excellent deliverability, detailed analytics, and a credit system that never expires. If you're scaling your business and expect to send more than the free 300 emails/day from Brevo, ZeptoMail is a fantastic next step.

ZeptoMail SMTP Settings at a Glance

Setting	Value
SMTP Host	`smtp.zeptomail.com` Copy
Port	`587`
Encryption	`STARTTLS`
Username	The unique Email Address generated for your Mail Agent (e.g., `[email protected]`)
Password	The unique Password (Token) generated for your Mail Agent
FROM Email	Any email address from your verified domain (e.g., `[email protected]`)

⚠️ Two important ZeptoMail concepts:
1. Your Username is the special email address generated by ZeptoMail for your Mail Agent — it is not your Zoho login email or your FROM email.
2. Your Password is the unique token generated for that Mail Agent. You must verify your domain with SPF and DKIM records; otherwise, your emails may be rejected.

Step-by-Step Setup

1

Create a ZeptoMail account

Go to zeptomail.com and sign up for a free trial or choose a paid plan. ZeptoMail is a transactional email service by Zoho, designed specifically for application-sent emails like business replies.
Open ZeptoMail Dashboard →
2

Add and verify your sending domain

In your ZeptoMail dashboard, go to Settings → Domains. Click "Add Domain", enter your domain (e.g., yourbusiness.com), and follow the instructions to add the provided DNS records (SPF, DKIM, and possibly MX records) to your domain's DNS settings. This proves you own the domain and improves email deliverability.
Open ZeptoMail Dashboard →
3

Create a Mail Agent (Transactional)

Go to Mail Agents → Create Mail Agent. Choose "Transactional" as the type. Select your verified domain and enter a name like "Mail AI Replies". This Mail Agent will provide you with the SMTP credentials.
Open ZeptoMail Dashboard →
4

Generate SMTP credentials for your Mail Agent

After creating the Mail Agent, click on it to view its details. Go to the "SMTP" tab and click "Generate SMTP Token". Copy the generated Email Address and Password (Token). These are your unique SMTP credentials for this Mail Agent.
Open ZeptoMail Dashboard →
5

Open Reply SMTP Setting in Mail AI

In your Mail AI dashboard, go to Linked Email Accounts. Find the email address you want to configure and click "+ Reply SMTP Setting".
Open Mail AI Dashboard →
6

Select ZeptoMail and enter credentials

Choose ZeptoMail from the provider list. Enter the **Email Address** generated in Step 4 as the **Username**. Paste the **Password (Token)** from Step 4 into the password field. Enter your FROM email address (must be from your verified domain) and your name or business name. SMTP host and port are pre-filled automatically.
Open Mail AI Dashboard →
7

Save and verify the connection

Click Save SMTP. Mail AI tests the connection instantly. A green "Custom SMTP ✓" badge appears on your linked email card when successful. Your AI replies will now be delivered via ZeptoMail's high-performance infrastructure.
Open Mail AI Dashboard →

✅ Success looks like: After saving, your linked email card in the Mail AI dashboard shows a green "Custom SMTP ✓" badge. Your AI-drafted replies will now be delivered via ZeptoMail's reliable infrastructure, from your verified domain address.

Troubleshooting Common ZeptoMail SMTP Errors

"Domain not verified" or "Sender address not allowed"

This is the most common ZeptoMail error. It means your FROM email address (e.g., [email protected]) is from a domain that hasn't been verified in ZeptoMail. Go to ZeptoMail → Settings → Domains, add your domain, and add the provided DNS records (SPF and DKIM). This can take 10-30 minutes to propagate after you save the records in your DNS.

"Authentication failed" or "Username/Password incorrect"

Double-check that you are using the exact Email Address and Password (Token) generated for your Mail Agent in the SMTP tab. Do not use your Zoho account login credentials. If you've lost your token, go to your Mail Agent in ZeptoMail, go to the SMTP tab, and generate a new token.

SMTP connection fails / "Connection timed out"

Ensure you are using the correct host (smtp.zeptomail.com) and port (587) with STARTTLS. ZeptoMail does not use port 465. Also, check that your hosting provider or local network allows outbound connections on port 587.

My email credits are not being used / emails are not sending

Check your ZeptoMail dashboard for any alerts. You may have run out of credits. New accounts often start with a trial balance. You can purchase additional credit packs in the ZeptoMail billing section.

ZeptoMail vs Brevo — Which One for Mail AI?

Feature	🟠 ZeptoMail	💚 Brevo
Custom domain email (e.g., [email protected])	✅ Yes (with domain verification)	✅ Yes (with sender verification)
Pricing Model	Pay-as-you-go credits (never expire)	Free plan (300/day) or monthly subscription
Best for...	High volume, scale, and pay-as-you-go flexibility	Low-to-medium volume, simple free plan
Setup complexity	Requires adding DNS records (SPF, DKIM)	Simple email/sender verification
Domain reputation control	✅ Full (SPF/DKIM on your domain)	✅ Yes

Rule of thumb: use 💚 Brevo if you want the simplest free setup. Use 🟠 ZeptoMail if you are sending a high volume of replies (hundreds per day), prefer a pay-as-you-go model, or are already familiar with Zoho's ecosystem.

ZeptoMail Sending Limits & Pricing Summary

Free trial: New accounts usually start with a trial credit (e.g., 1000 emails) to test the service.
Credit packs: You purchase credits in packs (e.g., 10,000 emails for a flat fee). Credits never expire, so you only pay for what you use.
No daily limits: Unlike Brevo's free plan (300/day), ZeptoMail has no daily cap — you can send as many replies as you have credits for.
For most businesses using Mail AI, a one-time credit purchase can last for months, making it very cost-effective.

Ready to Send?

With ZeptoMail SMTP connected, your Mail AI workflow is ready for scale: customer emails arrive, the AI summarises and drafts a reply, and when you click Send it leaves from your own business email address — professionally branded, fully threaded, and delivered with enterprise-grade reliability.

Go to your Mail AI dashboard →