Add generic SMTP server configuration example

Add a basic SMTP example that works with any standard SMTP server,
positioned before the specific provider examples (Gmail, SendGrid, etc.).

Includes:
- Generic SMTP configuration template
- Clear explanation of EMAIL_USE_TLS vs EMAIL_USE_SSL
- Common SMTP port reference (587, 465, 25)
- Notes on which settings to use for each port

This provides a starting point for users with custom mail servers
or SMTP providers not specifically listed in the documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

README.md

@@ -701,6 +701,25 @@ exit
 
 Choose one of the following email providers:
 
+**Generic SMTP Server (Any Provider):**
+
+For any standard SMTP server (custom mail server, hosting provider, etc.):
+
+```env
+EMAIL_HOST=smtp.yourdomain.com
+EMAIL_PORT=587                    # Use 587 for TLS or 465 for SSL
+EMAIL_USE_TLS=True               # Set to True for port 587
+EMAIL_USE_SSL=False              # Set to True for port 465 (not both TLS and SSL)
+EMAIL_HOST_USER=noreply@yourdomain.com
+EMAIL_HOST_PASSWORD=your-smtp-password
+DEFAULT_FROM_EMAIL=KeepItGoing <noreply@yourdomain.com>
+```
+
+**Common SMTP ports:**
+- Port 587: STARTTLS (recommended) - use `EMAIL_USE_TLS=True`
+- Port 465: SSL/TLS - use `EMAIL_USE_SSL=True`
+- Port 25: Unencrypted (not recommended)
+
 **Gmail:**
 1. Enable 2-factor authentication on your Google account
 2. Generate an App Password: https://myaccount.google.com/apppasswords