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fix: route inbound email by envelope recipient #33

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fix: route inbound email by envelope recipient #33

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2 changes: 1 addition & 1 deletion workers/app.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,7 @@ app.all("*", (c) => {
export default {
fetch: app.fetch,
async email(
event: { raw: ReadableStream; rawSize: number },
event: { raw: ReadableStream; rawSize: number; to?: string },
env: Env,
ctx: ExecutionContext,
) {
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27 changes: 19 additions & 8 deletions workers/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -329,6 +329,12 @@ app.get("/api/v1/mailboxes/:mailboxId/emails/:emailId/attachments/:attachmentId"

const MAX_EMAIL_SIZE = 25 * 1024 * 1024;

type InboundEmailEvent = {
raw: ReadableStream;
rawSize: number;
to?: string;
};

async function streamToArrayBuffer(stream: ReadableStream, streamSize: number) {
if (streamSize > MAX_EMAIL_SIZE) throw new Error(`Email too large: ${streamSize} bytes exceeds ${MAX_EMAIL_SIZE} byte limit`);
if (streamSize <= 0) throw new Error(`Invalid stream size: ${streamSize}`);
Expand All @@ -345,22 +351,27 @@ async function streamToArrayBuffer(stream: ReadableStream, streamSize: number) {
return result;
}

async function receiveEmail(event: { raw: ReadableStream; rawSize: number }, env: Env, ctx: ExecutionContext) {
function normalizeEmailAddress(address?: string | null) {
return address?.trim().toLowerCase() || undefined;
}

async function receiveEmail(event: InboundEmailEvent, env: Env, ctx: ExecutionContext) {
const rawEmail = await streamToArrayBuffer(event.raw, event.rawSize);
const parsedEmail = await new PostalMime().parse(rawEmail);

if (!parsedEmail.to?.length || !parsedEmail.to[0].address) throw new Error("received email with empty to");

const allowedAddresses = ((env.EMAIL_ADDRESSES ?? []) as string[]).map((a) => a.toLowerCase());
const allRecipients = parsedEmail.to.map((t) => t.address?.toLowerCase()).filter(Boolean) as string[];
const ccRecipients = (parsedEmail.cc || []).map((e) => e.address?.toLowerCase()).filter(Boolean) as string[];
const bccRecipients = (parsedEmail.bcc || []).map((e) => e.address?.toLowerCase()).filter(Boolean) as string[];
const envelopeRecipient = normalizeEmailAddress(event.to);
const headerRecipients = (parsedEmail.to || []).map((t) => normalizeEmailAddress(t.address)).filter(Boolean) as string[];
const routingRecipients = envelopeRecipient ? [envelopeRecipient] : headerRecipients;
const allRecipients = headerRecipients.length > 0 ? headerRecipients : routingRecipients;
const ccRecipients = (parsedEmail.cc || []).map((e) => normalizeEmailAddress(e.address)).filter(Boolean) as string[];
const bccRecipients = (parsedEmail.bcc || []).map((e) => normalizeEmailAddress(e.address)).filter(Boolean) as string[];

let mailboxId: string | undefined;
if (allowedAddresses.length > 0) {
mailboxId = allRecipients.find((addr) => allowedAddresses.includes(addr));
mailboxId = routingRecipients.find((addr) => allowedAddresses.includes(addr));
if (!mailboxId) { console.log(`Ignoring email: no recipient matches EMAIL_ADDRESSES.`); return; }
} else { mailboxId = allRecipients[0]; }
} else { mailboxId = routingRecipients[0]; }
if (!mailboxId) throw new Error("received email with no valid recipient address");

const messageId = crypto.randomUUID();
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