Add beforeSend hook for email customization

- Add BeforeSendHook type and BeforeSendMailOptions interface
- Implement hook execution in MailingService before sending emails
- Hook allows adding attachments, headers, and modifying email options
- Add comprehensive documentation with examples
- Bump version to 0.1.20

README.md

@@ -142,6 +142,18 @@ mailingPlugin({
   richTextEditor: lexicalEditor(),  // optional custom editor
   onReady: async (payload) => {     // optional initialization hook
     console.log('Mailing plugin ready!')
+  },
+
+  // beforeSend hook - modify emails before sending
+  beforeSend: async (options, email) => {
+    // Add attachments, modify headers, etc.
+    options.attachments = [
+      { filename: 'invoice.pdf', content: pdfBuffer }
+    ]
+    options.headers = {
+      'X-Campaign-ID': email.campaignId
+    }
+    return options
   }
 })
 ```
@@ -255,6 +267,56 @@ mailingPlugin({
 })
 ```
 
+### beforeSend Hook
+
+Modify emails before they are sent to add attachments, custom headers, or make other changes:
+
+```typescript
+mailingPlugin({
+  // ... other config
+  beforeSend: async (options, email) => {
+    // Add attachments dynamically
+    if (email.invoiceId) {
+      const invoice = await generateInvoicePDF(email.invoiceId)
+      options.attachments = [
+        {
+          filename: `invoice-${email.invoiceId}.pdf`,
+          content: invoice.buffer,
+          contentType: 'application/pdf'
+        }
+      ]
+    }
+
+    // Add custom headers
+    options.headers = {
+      'X-Campaign-ID': email.campaignId,
+      'X-Customer-ID': email.customerId,
+      'X-Priority': email.priority === 1 ? 'High' : 'Normal'
+    }
+
+    // Modify recipients based on conditions
+    if (process.env.NODE_ENV === 'development') {
+      // Redirect all emails to test address in dev
+      options.to = ['test@example.com']
+      options.subject = `[TEST] ${options.subject}`
+    }
+
+    // Add BCC for compliance
+    if (email.requiresAudit) {
+      options.bcc = ['audit@company.com']
+    }
+
+    return options
+  }
+})
+```
+
+The `beforeSend` hook receives:
+- `options`: The nodemailer mail options that will be sent
+- `email`: The full email document from the database
+
+You must return the modified options object.
+
 ### Initialization Hooks
 
 Control plugin initialization order and add post-initialization logic:
@@ -266,7 +328,7 @@ mailingPlugin({
   onReady: async (payload) => {
     // Called after plugin is fully initialized
     console.log('Mailing plugin ready!')
-    
+
     // Custom initialization logic here
     await setupCustomEmailSettings(payload)
   }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@xtr-dev/payload-mailing",
-  "version": "0.1.19",
+  "version": "0.1.20",
   "description": "Template-based email system with scheduling and job processing for PayloadCMS",
   "type": "module",
   "main": "dist/index.js",

src/sendEmail.ts

@@ -83,25 +83,25 @@ export const sendEmail = async <TEmail extends BaseEmailDocument = BaseEmailDocu
   if (emailData.to) {
     emailData.to = parseAndValidateEmails(emailData.to as string | string[])
   }
-  if (emailData.cc && emailData.cc !== null) {
+  if (emailData.cc) {
     emailData.cc = parseAndValidateEmails(emailData.cc as string | string[])
   }
-  if (emailData.bcc && emailData.bcc !== null) {
+  if (emailData.bcc) {
     emailData.bcc = parseAndValidateEmails(emailData.bcc as string | string[])
   }
-  if (emailData.replyTo && emailData.replyTo !== null) {
+  if (emailData.replyTo) {
     const validated = parseAndValidateEmails(emailData.replyTo as string | string[])
     // replyTo should be a single email, so take the first one if array
     emailData.replyTo = validated && validated.length > 0 ? validated[0] : undefined
   }
-  if (emailData.from && emailData.from !== null) {
+  if (emailData.from) {
     const validated = parseAndValidateEmails(emailData.from as string | string[])
     // from should be a single email, so take the first one if array
     emailData.from = validated && validated.length > 0 ? validated[0] : undefined
   }
 
   // Sanitize fromName to prevent header injection
-  if (emailData.fromName && emailData.fromName !== null) {
+  if (emailData.fromName) {
     emailData.fromName = emailData.fromName
       .trim()
       // Remove/replace newlines and carriage returns to prevent header injection

src/services/MailingService.ts

@@ -270,7 +270,7 @@ export class MailingService implements IMailingService {
         fromField = this.getDefaultFrom()
       }
 
-      const mailOptions = {
+      let mailOptions: any = {
         from: fromField,
         to: email.to,
         cc: email.cc || undefined,
@@ -281,6 +281,16 @@ export class MailingService implements IMailingService {
         text: email.text || undefined,
       }
 
+      // Call beforeSend hook if configured
+      if (this.config.beforeSend) {
+        try {
+          mailOptions = await this.config.beforeSend(mailOptions, email)
+        } catch (error) {
+          console.error('Error in beforeSend hook:', error)
+          throw new Error(`beforeSend hook failed: ${error instanceof Error ? error.message : 'Unknown error'}`)
+        }
+      }
+
       await this.transporter.sendMail(mailOptions)
 
       await this.payload.update({

src/types/index.ts

@@ -48,6 +48,21 @@ export type TemplateRendererHook = (template: string, variables: Record<string,
 
 export type TemplateEngine = 'liquidjs' | 'mustache' | 'simple'
 
+export interface BeforeSendMailOptions {
+  from: string
+  to: string[]
+  cc?: string[]
+  bcc?: string[]
+  replyTo?: string
+  subject: string
+  html: string
+  text?: string
+  attachments?: any[]
+  [key: string]: any
+}
+
+export type BeforeSendHook = (options: BeforeSendMailOptions, email: BaseEmailDocument) => BeforeSendMailOptions | Promise<BeforeSendMailOptions>
+
 export interface MailingPluginConfig {
   collections?: {
     templates?: string | Partial<CollectionConfig>
@@ -62,6 +77,7 @@ export interface MailingPluginConfig {
   templateRenderer?: TemplateRendererHook
   templateEngine?: TemplateEngine
   richTextEditor?: RichTextField['editor']
+  beforeSend?: BeforeSendHook
   onReady?: (payload: any) => Promise<void>
   initOrder?: 'before' | 'after'
 }