feat(xo-server-transport-email): ability to customize transport settings (#5681)

See xoa-support#3327

This functionnality can help users to get more info about their SMTP issues

CHANGELOG.unreleased.md

@@ -31,6 +31,7 @@
 >
 > In case of conflict, the highest (lowest in previous list) `$version` wins.
 
+- xo-server-transport-email minor
 - @xen-orchestra/fs minor
 - xo-server patch
 - xo-web patch

packages/xo-server-transport-email/src/index.js

@@ -128,7 +128,8 @@ export const testSchema = {
 // ===================================================================
 
 class TransportEmailPlugin {
-  constructor({ xo }) {
+  constructor({ staticConfig, xo }) {
+    this._staticConfig = staticConfig
     this._xo = xo
     this._unset = null
 
@@ -157,7 +158,7 @@ class TransportEmailPlugin {
         break
     }
 
-    const transport = createTransport(transportConf, { from })
+    const transport = createTransport({ ...transportConf, ...this._staticConfig.transport }, { from })
     transport.use('compile', markdownCompiler)
 
     this._send = promisify(transport.sendMail, transport)