Update email code to send an email per EditUserCell

using multiple recipients is break of privacy since user will be able
to see each other's emails.

app/api/src/graphql/email.sdl.ts

@@ -7,8 +7,6 @@ export const schema = gql`
   type EmailResponse {
     accepted: [String!]!
     rejected: [String!]!
-    messageId: String!
-    envelope: Envelope
   }
 
   input Email {

app/api/src/lib/sendmail.ts

@@ -1,7 +1,7 @@
 import nodemailer, { SendMailOptions } from 'nodemailer'
 
-interface Args {
-  to: SendMailOptions['to']
+export interface SendMailArgs {
+  to: string
   from: SendMailOptions['from']
   subject: string
   text: string
@@ -26,7 +26,7 @@ export function sendMail({
   from,
   subject,
   text,
-}: Args): Promise<SuccessResult> {
+}: SendMailArgs): Promise<SuccessResult> {
   const transporter = nodemailer.createTransport({
     host: 'smtp.mailgun.org',
     port: 587,

app/api/src/services/email/email.ts

@@ -1,26 +1,45 @@
 import { requireAuth } from 'src/lib/auth'
 import { sendMail } from 'src/lib/sendmail'
+import type { SendMailArgs } from 'src/lib/sendmail'
 import { users } from 'src/services/users/users'
 
 export const sendAllUsersEmail = async ({ input: { body, subject } }) => {
   requireAuth({ role: 'admin' })
-  const recipients = (await users()).map(({ email }) => email)
   const from = {
     address: 'news@mail.cadhub.xyz',
     name: 'CadHub',
   }
-  const result = await sendMail({
-    to: recipients,
+  const emails: SendMailArgs[] = (await users()).map(({ email }) => ({
+    to: email,
     from,
     subject,
     text: body,
+  }))
+  const emailPromises = emails.map((email) => sendMail(email))
+  const accepted = []
+  const rejected = []
+  const result = await Promise.allSettled(emailPromises)
+  result.forEach((result) => {
+    if (result.status === 'fulfilled') {
+      accepted.push(result.value.accepted[0])
+    } else {
+      rejected.push(result.reason)
+    }
   })
   await sendMail({
     to: 'k.hutten@protonmail.ch',
     from,
     subject: `All users email report`,
-    text: JSON.stringify(result, null, 2),
+    text: JSON.stringify(
+      {
+        accepted,
+        rejected,
+        originalEmailList: emails,
+      },
+      null,
+      2
+    ),
   })
 
-  return result
+  return { accepted, rejected }
 }