Mailboxes over IMAP and JMAP.

Dashboard → Mailboxes → you@yourdomain.com
Click  [ + App password ]        (copy it — shown once)

Point any mail app at:
  Incoming  IMAP  imap.mailkite.dev : 993   (TLS)
  Username        you@yourdomain.com
  Password        <the app password>

Outbound goes through the Send API or the SMTP relay,
SPF/DKIM aligned to your domain.

import { ImapFlow } from "imapflow";

const client = new ImapFlow({
  host: "imap.mailkite.dev",
  port: 993,
  secure: true,
  auth: { user: "you@yourdomain.com", pass: process.env.MAILKITE_IMAP_PASSWORD },
});

await client.connect();
const lock = await client.getMailboxLock("INBOX");
try {
  for await (const msg of client.fetch({ seen: false }, { source: true })) {
    handle(msg.source);
  }
} finally {
  lock.release();
}
await client.logout();

import imaplib

m = imaplib.IMAP4_SSL("imap.mailkite.dev", 993)
m.login("you@yourdomain.com", APP_PASSWORD)   # from the dashboard
m.select("INBOX")

_, data = m.search(None, "UNSEEN")
for num in data[0].split():
    _, msg = m.fetch(num, "(RFC822)")
    handle(msg[0][1])

<?php
$mbox = imap_open(
    "{imap.mailkite.dev:993/imap/ssl}INBOX",
    "you@yourdomain.com",
    getenv("MAILKITE_IMAP_PASSWORD")
);

foreach (imap_search($mbox, "UNSEEN") ?: [] as $num) {
    handle(imap_fetchbody($mbox, $num, ""));
}
imap_close($mbox);

Properties props = new Properties();
props.put("mail.store.protocol", "imaps");
Session session = Session.getInstance(props);

Store store = session.getStore("imaps");
store.connect("imap.mailkite.dev", 993, "you@yourdomain.com", System.getenv("MAILKITE_IMAP_PASSWORD"));

Folder inbox = store.getFolder("INBOX");
inbox.open(Folder.READ_ONLY);

for (Message msg : inbox.search(new FlagTerm(new Flags(Flags.Flag.SEEN), false))) {
    handle(msg);
}

c, err := client.DialTLS("imap.mailkite.dev:993", nil)
if err != nil { log.Fatal(err) }
defer c.Logout()

if err := c.Login("you@yourdomain.com", os.Getenv("MAILKITE_IMAP_PASSWORD")); err != nil {
    log.Fatal(err)
}
c.Select("INBOX", false)

criteria := imap.NewSearchCriteria()
criteria.WithoutFlags = []string{imap.SeenFlag}
uids, _ := c.Search(criteria)

seqset := new(imap.SeqSet)
seqset.AddNum(uids...)
messages := make(chan *imap.Message, 10)
go c.Fetch(seqset, []imap.FetchItem{imap.FetchRFC822}, messages)
for msg := range messages { handle(msg) }

require "net/imap"

imap = Net::IMAP.new("imap.mailkite.dev", port: 993, ssl: true)
imap.login("you@yourdomain.com", ENV["MAILKITE_IMAP_PASSWORD"])
imap.select("INBOX")

imap.search(["UNSEEN"]).each do |id|
  raw = imap.fetch(id, "RFC822")[0].attr["RFC822"]
  handle(raw)
end
imap.logout

# IMAP over TLS — curl speaks it, so you can check credentials
# without a mail client.
curl --ssl-reqd "imaps://imap.mailkite.dev/INBOX?UNSEEN" \
  -u "you@yourdomain.com:$MAILKITE_IMAP_PASSWORD"