When Your IBM i Email Delivery Fails with Office 365 or Gmail

We’ve been receiving about one request per week to help clients troubleshoot or fix SMTP email issues on IBM i systems—especially when sending to Microsoft (Office 365) and Gmail accounts.

These problems can affect a wide range of systems, including:

• RPG applications that send email
• Mail Server Framework (MSF)
• The SNDSMTPEMM (Send SMTP E-mail Message) command
• PHP applications
• Older third-party software still running since the AS/400 era

Most of the time, the issue appears when emailed reports or alerts stop going out.

What’s Causing These IBM i Email Problems?

The most common causes are recent changes made by Microsoft and Google to tighten email security. Occasionally, the IBM i system itself is the source—especially after system or configuration changes.

Typical factors include:

• TLS-encrypted connections with authentication are now required by Office 365 and Gmail
• Microsoft “app password” requirements, instead of standard account passwords
• OAuth replacing Basic Authentication for some Microsoft services (enforcement expected spring 2026)
• Internal changes, such as moving to a new data center or changing SMTP relay services

Fixes Depend on the Situation

The solution varies depending on your setup. Two recent examples we’ve seen:

• A client needed to update their certificates in the IBM i Digital Certificate Manager (DCM)
• Another had incorrect domain name settings

Resources from IBM

If you’re comfortable working on your own configuration, IBM provides two excellent guides for SMTP setup:

• How to configure the SMTP client to use authentication and relay
• Configuring the IBM i SMTP client for Office 365 and Gmail

We Can Help

If your IBM i system is no longer sending email reliably—especially to Gmail or Office 365 recipients—you’re not alone. We’ve helped many clients resolve these issues quickly and effectively.

Need assistance? Contact us with details about your situation. We’re here to help.