Modified on: Wed, 28 Jan, 2026 at 7:26 AM

Initial Recommendations

Scalendo offers direct integrations with Google and Outlook that should be used instead of SMTP. Alternative built-in options include:

• Gmail Sync: Two-way email synchronization for Gmail accounts
• Outlook Integration: Two-way email sync for Outlook
• Scalendo Email: Built-in bulk sending capability

The documentation notes that "If you choose to use SMTP you do so at your own discretion, while we offer support it will be done on a best effort basis."

SMTP Server Resources

A comprehensive list of SMTP and IMAP servers is available at: https://www.arclab.com/en/kb/email/list-of-smtp-and-imap-servers-mailserver-list.html

Sender Email Address Configuration

When using your own SMTP provider, the sender email must match the integrated SMTP email address. If they don't align or the sender email isn't verified with your SMTP provider, delivery will fail.

Testing SMTP Integration

For manual conversations, update the sender email to match the integrated SMTP email instead of using the default login email.

Email Sending Limits

SMTP providers may impose daily sending limits. Gmail, for example, allows approximately 100-150 emails daily when connected via remote client.

Email Statistics Limitations

"SMTP integration will show opened and clicked only" -- delivered and bounced stats aren't available. Mailgun or Scalendo Email integration is recommended for comprehensive statistics.

Common Setup Issues

1. Disable Email Re-Billing while making provider changes
2. Test credentials using the GMASS SMTP testing tool: https://www.gmass.co/smtp-test