Zoho splits its SMTP host across two products: free/personal accounts use smtp.zoho.com, paid Mail/Workplace organizations use smtppro.zoho.com. The hosts are not interchangeable - using the wrong one returns a generic "authentication failed" error with no clear hint as to why.
Regional SMTP hosts
If your Zoho account is on a non-US data center, swap the TLD on the host:
- US (default):
smtp.zoho.com/smtppro.zoho.com - EU:
smtp.zoho.eu/smtppro.zoho.eu - India:
smtp.zoho.in/smtppro.zoho.in - Australia:
smtp.zoho.com.au/smtppro.zoho.com.au
How to know which one is yours: Zoho Mail → Settings → Mail Accounts → Server Configuration Details. The exact host for your account is shown there. Always confirm there before saving in Inflowave.
Generate your app-specific password
- Sign in to
accounts.zoho.com. - Left sidebar, Security, then App Passwords.
- Click Generate New Password, name it "Inflowave SMTP".
- Copy the generated password.
2FA prerequisite: App Passwords only appear under Security if you have Two-Factor Authentication enabled. If you do not see the App Passwords option, enable 2FA first (Security → Multi-Factor Authentication).
Connect to Inflowave
- Inflowave → Settings → Email → Add sending domain → Custom SMTP.
- Host: the correct host from the table above for your tier and region.
- Port:
587. - Username: your full Zoho email.
- Password: the App-Specific Password.
- Save and test.
Troubleshooting
Wrong tier host (you used smtp.zoho.com on a paid account or smtppro.zoho.com on a free account), wrong region, or wrong password. Re-check all three.
Your sending email address does not match the Zoho account that owns the App Password, OR an alias configured on that account. Send as the same address you used to authenticate.
2FA is not enabled on the Zoho account. Turn it on at accounts.zoho.com → Security → Multi-Factor Authentication.
