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How do I generate an App specific for Zoho email?

Why am I getting 554 5.1.8 error code? Why are my emails sent twice?

Two-Factor Authentication (TFA) adds an extra layer of security to your Zoho account. With TFA enabled, logging in requires both your regular password and a one-time code — typically sent to your registered mobile number.

When TFA is enabled, third-party applications or external email clients (e.g. IMAP/POP clients, CRM platforms, mobile mail apps) cannot use your regular password for authentication. Instead, they require a unique, app-specific password.

When Do You Need an App-Specific Password?

Use an app-specific password if:

  • You have enabled TFA for your Zoho account

  • You’re setting up Zoho Mail in a third-party app or client (e.g. desktop/mobile email client, CRM tool) that doesn’t support Zoho’s native authentication flow

How to Generate an App-Specific Password — Step by Step

  1. Log in to your Zoho account

  2. Navigate to Security → App Passwords in your account settings

  3. Click Generate New Password

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  4. In the dialog/pop-up, enter a name for the app (e.g. “Outlook,” “Mobile Mail,” “CRM Tool”). — the name is for your reference only.

  5. Click Generate. A 12- or 16-digit “application-specific password” will be created.

  6. Copy the password immediately and save it securely — it won’t be shown again.

  7. Use this app-specific password (instead of your regular Zoho password) when configuring your third-party application or email client.

  8. Go back to your Investor Matching Email account setup page:
    https://www.startups.com/investors/matching

  9. Paste the generated password in both the SMTP Password and IMAP Password fields.

  10. Click Test Account to verify that the connection is working successfully.

  11. Once it shows Connected, your email account will be connected and ready to use.

554 5.1.8 Sender Address Blocked

This error indicates that Zoho has restricted your email address from sending outgoing messages due to policy or security concerns.
To resolve this, you must contact Zoho Support so they can review the restriction and unblock your sender address.

Emails Being Sent Twice 

If you notice that emails sent from your Zoho email account are appearing twice in the Sent folder (or recipients report duplicate sends), this is usually caused by a Zoho Mail SMTP setting—not an issue with Startups.com or the app password itself.

Why This Happens

Zoho Mail has an option that automatically saves a copy of sent emails when using SMTP. When your email client or service already saves sent messages, this setting can cause duplicates.

How to Fix It

You’ll need to update the setting directly in Zoho Mail:

  1. Log in to Zoho Mail using your web browser.

  2. Go to Settings.

  3. Navigate to Mail Accounts.

  4. Select your email account.

  5. Open the General tab.

  6. Locate the SMTP section.

  7. Untick the option labeled “Save a copy of sent emails.”

  8. Save your changes.

Once this setting is disabled, emails should no longer be duplicated.

Note: This change must be made in the Zoho Mail web interface. It cannot be fixed from within Startups.com or your email client.