# Using CRM-NG SMTP on a WordPress multisite

Source: https://catalystgroup.gg/docs/email-delivery/multisite/
Updated: 2026-10-19 · By Duane Garner

How CRM-NG SMTP behaves on a multisite network, where its settings live, who can change them, and how to share one setup across sites.

This article explains how CRM-NG SMTP works on a WordPress multisite network. It is for network administrators and site administrators on a network.

 

## Activating on a network

 

You can activate CRM-NG SMTP in two ways:

 
- **Network Activate** from **Network Admin → Plugins**. The plugin runs on every site in the network.
- **Activate** on individual sites from each site's **Plugins** page, if the network allows site administrators to manage plugins.

 

Either way, each site gets its own **CRM-NG SMTP** menu.

 

## Per-site settings (the default)

 

By default, every site in the network has **its own** CRM-NG SMTP settings. Each site can use a different sender, a different mailer and different credentials. This suits networks where each site belongs to a different brand or client.

 

Per-site means:

 
- Each site's settings are stored in that site's own `crmng_smtp` option.
- Each site keeps its own email log, debug events and reports.
- A site administrator (anyone with the **manage_options** capability on that site) can change that site's settings at **CRM-NG SMTP → Settings**.
- Uninstall clean-up, if you turn it on, also runs site by site.

 

## One setup for the whole network

 

Many networks want every site to send the same way, through one account, without each site administrator filling in the form. There are two ways to get there.

 

### Option 1: wp-config.php constants (recommended)

 

All sites in a network share one `wp-config.php` file, so settings you define there apply to every site at once, and nobody can change them from the admin screens.

 

```
define( 'CRMNG_SMTP_ON', true );
define( 'CRMNG_SMTP_MAIL_FROM', 'noreply@yournetwork.com' );
define( 'CRMNG_SMTP_MAIL_FROM_FORCE', true );
define( 'CRMNG_SMTP_MAIL_FROM_NAME', 'Your Network' );
define( 'CRMNG_SMTP_MAILER', 'sendinblue' );
define( 'CRMNG_SMTP_SENDINBLUE_API_KEY', 'your-key-here' );
```

 

Fields set by a constant show as locked on the settings screen. You can set only some values as constants (for example the mailer and its key) and let each site set its own sender name. The full list of constants and how they work is in [Securing settings with wp-config constants](https://catalystgroup.gg/docs/email-delivery/secure-settings-constants/).

 

This is also the safest place for API keys, because they are not stored in the database.

 

### Option 2: network-wide mode

 

CRM-NG SMTP can also keep a single set of settings for the whole network, stored on the main site. When this mode is on:

 
- Every site reads the main site's settings.
- Changing the settings, running **Tools → Import** and pressing the hand-over buttons need the **manage_network_options** capability, which normally means a Super Admin.
- Site administrators can no longer change mail settings for their own site.

 

This version of CRM-NG SMTP has no switch on its screens to turn network-wide mode on. Use the constants in option 1 if you want one shared setup. If your network already had network-wide mode turned on, it keeps working, and an import never changes it.

 

## Testing on a network

 

Send a test from each site that matters, at **CRM-NG SMTP → Tools → Email Test**. Even with shared settings, each site may use a different From Email domain, and each domain needs its own SPF, DKIM and DMARC records. See [Adding DNS records](https://catalystgroup.gg/docs/email-delivery/dns-records/).

 

## Hand-over and imports on a network

 

If another mail plugin was configured network-wide on the main site, CRM-NG SMTP notices this on every site and starts in standby. Follow [Switching from another mail plugin (hand-over)](https://catalystgroup.gg/docs/email-delivery/switching-from-another-mail-plugin/) on each site where you want CRM-NG SMTP to take over.

 

## Conflicts on a network

 

If a conflicting mail plugin is network-activated, the conflict notice says so. Deactivate it from **Network Admin → Plugins**, not from a single site. See [Testing for plugin and theme conflicts](https://catalystgroup.gg/docs/email-delivery/plugin-and-theme-conflicts/).

 

## Related

 
- [Securing settings with wp-config constants](https://catalystgroup.gg/docs/email-delivery/secure-settings-constants/)
- [Setting up CRM-NG SMTP in five minutes](https://catalystgroup.gg/docs/email-delivery/first-setup/)
- [What the plugin stores and sends](https://catalystgroup.gg/docs/email-delivery/privacy-and-data/)
- [Switching from another mail plugin (hand-over)](https://catalystgroup.gg/docs/email-delivery/switching-from-another-mail-plugin/)