feat(api): allow routing all email through fallback (#3509)

fluxer_api/pkgs/email/src/DomainRoutedEmailProvider.test.ts

@@ -30,6 +30,16 @@ describe('DomainRoutedEmailProvider', () => {
 		expect(result).toBe(route === 'primary');
 	});
 
+	it('sends every address through the fallback provider when the domains are *', async () => {
+		const primary = {sendEmail: vi.fn().mockResolvedValue(true)};
+		const fallback = {sendEmail: vi.fn().mockResolvedValue(true)};
+		const provider = new DomainRoutedEmailProvider(primary, fallback, ['*']);
+		await provider.sendEmail(message('[email protected]'));
+		await provider.sendEmail(message('[email protected]'));
+		expect(fallback.sendEmail).toHaveBeenCalledTimes(2);
+		expect(primary.sendEmail).not.toHaveBeenCalled();
+	});
+
 	it('never reaches either provider for a bounced address', async () => {
 		const primary = {sendEmail: vi.fn().mockResolvedValue(true)};
 		const fallback = {sendEmail: vi.fn().mockResolvedValue(true)};

fluxer_api/pkgs/email/src/DomainRoutedEmailProvider.ts

@@ -21,7 +21,7 @@ export class DomainRoutedEmailProvider implements IEmailProvider {
 			.slice(message.to.lastIndexOf('@') + 1)
 			.trim()
 			.toLowerCase();
-		const useFallback = this.fallbackDomains.has(domain);
+		const useFallback = this.fallbackDomains.has('*') || this.fallbackDomains.has(domain);
 		logger.debug({domain, provider: useFallback ? 'fallback' : 'primary'}, 'Routing email');
 		return (useFallback ? this.fallback : this.primary).sendEmail(message);
 	}

fluxer_docs/src/content/docs/operator/configuration.mdx

@@ -843,7 +843,7 @@ A second SMTP provider can take the mail for chosen recipient domains while ever
 
 #### `FLUXER_EMAIL_FALLBACK_DOMAINS`
 
-Default empty. The recipient domains that go through the fallback provider, comma separated, such as `gmail.com,googlemail.com`. Matching ignores case and takes the part of the address after the last `@`. Only an exact match counts, so `gmail.com` leaves `mail.gmail.com` on the main provider. An entry that is not a bare domain fails startup. `.env.example` lists it commented out.
+Default empty. The recipient domains that go through the fallback provider, comma separated, such as `gmail.com,googlemail.com`. Matching ignores case and takes the part of the address after the last `@`. Only an exact match counts, so `gmail.com` leaves `mail.gmail.com` on the main provider. Set it to `*` alone to send every email through the fallback provider. An entry that is not a bare domain or `*` fails startup. `.env.example` lists it commented out.
 
 #### `FLUXER_EMAIL_FALLBACK_SMTP_HOST`
 

packages/config/src/ConfigLoader.ts

@@ -379,8 +379,11 @@ function normalizeEmailFallbackConfig(config: MasterConfig): void {
 	assertIntegerInRange(port, 'FLUXER_EMAIL_FALLBACK_SMTP_PORT', 1, 65_535);
 	validateSmtpHeaders(smtp.headers, 'FLUXER_EMAIL_FALLBACK_SMTP_HEADERS');
 	const normalizedDomains = domains.map((domain) => domain.trim().toLowerCase());
+	if (normalizedDomains.includes('*') && new Set(normalizedDomains).size > 1) {
+		throw new Error('FLUXER_EMAIL_FALLBACK_DOMAINS must be either * or a list of domains');
+	}
 	for (const domain of normalizedDomains) {
-		if (!EMAIL_DOMAIN_PATTERN.test(domain)) {
+		if (domain !== '*' && !EMAIL_DOMAIN_PATTERN.test(domain)) {
 			throw new Error(
 				`FLUXER_EMAIL_FALLBACK_DOMAINS entry ${JSON.stringify(domain)} must be a domain such as gmail.com`,
 			);

packages/config/src/__tests__/ConfigLoader.test.ts

@@ -540,6 +540,17 @@ describe('ConfigLoader', () => {
 		},
 	);
 
+	test('loads * as the email fallback domains', async () => {
+		stubMinimalEnv({...emailFallbackEnv, FLUXER_EMAIL_FALLBACK_DOMAINS: ' * '});
+		const config = await loadConfig();
+		expect(config.integrations.email.fallback?.domains).toEqual(['*']);
+	});
+
+	test('rejects * mixed with email fallback domains', async () => {
+		stubMinimalEnv({...emailFallbackEnv, FLUXER_EMAIL_FALLBACK_DOMAINS: '*,gmail.com'});
+		await expect(loadConfig()).rejects.toThrow('FLUXER_EMAIL_FALLBACK_DOMAINS must be either * or a list of domains');
+	});
+
 	test('loads the email fallback headers', async () => {
 		stubMinimalEnv({...emailFallbackEnv, FLUXER_EMAIL_FALLBACK_SMTP_HEADERS: '{"X-Tracking":"{\\"enable\\":0}"}'});
 		const config = await loadConfig();