SMTP2GO SMTP Settings and Configuration (2026)
Native SMTP relay, the specialist since 2006
SMTP2GO is a purpose-built SMTP relay, not a bolt-on. Point any client at mail.smtp2go.com on port 2525, 587 or 465, authenticate with SMTP credentials created in the dashboard, and outbound mail routes through with delivery reporting, DKIM signing and bounce handling out of the box.
SMTP2GO’s native relay is the fastest path when you need a transactional SMTP host for printers, WordPress, CRMs, or legacy servers that only speak SMTP. If you want a marketing-first sender, look at Mailchimp or Brevo; for developer-first APIs, compare with Postmark, Resend or SendGrid; for cheap high-volume infrastructure, Amazon SES or Mailgun deserve a benchmark run.
Quick reference
| SMTP server | mail.smtp2go.com · regional: mail-us, mail-eu, mail-eu2, mail-au.smtp2go.com |
| Port STARTTLS | 587 RECOMMENDED · also 25, 2525, 8025, 80 |
| Port SSL/TLS | 465 · also 8465, 443 |
| Alternative port | 2525 or 8025 when ISPs block 25/465/587 |
| Username | SMTP username created in dashboard under Sending › SMTP Users-not the account email |
| Password | Auto-generated SMTP password from the same SMTP Users panel, rotate per environment |
SMTP configuration
SMTP2GO relay endpoint
Transactional and bulk relay for apps, servers, printers and CRMs that speak SMTP.
Setup steps
- Sign up at smtp2go.com-the 1,000 emails/month free tier needs no credit card and lets you send within minutes.
- Add and verify your sending domain under Sending › Sender Domains. SMTP2GO issues two CNAME records (Return-Path subdomain + DKIM selector), publish them in your DNS.
- Create an SMTP user under Sending › SMTP Users. Copy the auto-generated username and password, the password is shown once.
- Configure your client: host mail.smtp2go.com, port 587, STARTTLS on, auth PLAIN/LOGIN with the credentials from step 3.
- Send a test message and watch Reporting › Activity for the delivery event. Bounces, opens and clicks flow into the same feed within seconds.
Authentication
SPF and DKIM setup
SMTP2GO’s recommended flow uses a per-domain Return-Path subdomain (em<XXXX>.yourdomain.com) CNAME’d to SMTP2GO, so the envelope-from lives on your own domain and a direct SPF include on your root is not required. The legacy manual mechanism is still supported when you cannot delegate the subdomain:
; Recommended (CNAME-based, generated per domain in dashboard): emXXXX.yourdomain.com. CNAME return.smtp2go.net. sXXXXXXX._domainkey.yourdomain.com. CNAME dkim.smtp2go.net. ; Legacy manual SPF include (only if you cannot delegate the subdomain): yourdomain.com. TXT "v=spf1 include:spf.smtp2go.com ~all"
Selector names and exact CNAME targets are generated per-domain in the SMTP2GO dashboard. Publish both CNAMEs, hit Verify, and DKIM signing kicks in on the next relayed message. Unlike Amazon SES, there is no separate MAIL FROM domain to configure, the Return-Path CNAME handles both.
DMARC alignment
SMTP2GO does not publish a DMARC record for you, add your own TXT record and start in monitoring mode. Because the Return-Path is on a subdomain, strict DKIM alignment (adkim=s) works cleanly but strict SPF alignment (aspf=s) will fail. Ramp progressively:
; Week 1, monitor yourdomain.com. TXT "v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com" ; Week 4+, enforce with strict DKIM only yourdomain.com. TXT "v=DMARC1; p=quarantine; adkim=s; aspf=r; pct=100; rua=mailto:dmarc@yourdomain.com"
Rate limits & sending caps
| Limit | Value | Notes |
|---|---|---|
| Emails / hour | 200,000 | Default account-wide max sending speed. Higher throughput is arranged with support on Premier plans. |
| Recipients / message | 400 total (To/CC/BCC) | API per-field cap is 100. SMTP2GO recommends 50-100 for deliverability. |
| Concurrent SMTP connections | 40 simultaneous | Up to 5,000 messages per open connection, keep sockets warm. |
| API requests / minute | 60 on /activity/search | Other endpoints have per-key limits configurable in dashboard. No universal RPM cap published. |
| Message size | 50 MB | Content + attachments + headers combined. API request body cap is 1 MB on standard endpoints, 50 MB on email endpoints (enforced June 11, 2026). |
Common setup gotchas
Use ports 2525 or 8025 when your host blocks the standard SMTP ports
SMTP2GO exposes TLS/STARTTLS on 25, 587, 2525, 8025 and 80, and SSL on 465, 8465 and 443. Most residential ISPs, AWS EC2, and shared hosts block outbound 25 (and often 465/587). SMTP2GO’s own docs call out 2525 and 8025 as unblocked fallbacks, try them first on scan-to-email printers or CI runners before opening a support ticket.
The From: address must be under a verified sender domain OR a verified single sender
Domain verification is CNAME-based (two records. Return-Path and DKIM) and applied per sending domain. If you cannot delegate DNS, verify individual From: addresses under Single Senders (up to 5 on the free tier). Attempting to send from an unverified address returns an API error and a 550 SMTP rejection, there is no “sender identity” shortcut as on SendGrid.
Strict SPF alignment will break, use strict DKIM only
Because SMTP2GO uses a per-domain Return-Path subdomain (em<XXXX>.yourdomain.com CNAME’d to smtp2go.net), the envelope-from is already on your domain but not identical to the header From. DMARC set to adkim=s aspf=s will fail SPF alignment. Use adkim=s aspf=r as SMTP2GO recommends. DKIM signing is the durable identity check anyway.
Free tier is 1,000/month AND 200/day, the daily cap bites first
The 1,000 emails/month free allowance is throttled to 200 emails per 24 hours. Automated jobs (welcome drips, backup notifications, WordPress cron) that spike above 200/day get 4xx responses on the free plan even if the monthly counter has room. Upgrade to Starter ($10/mo, 10,000/month) as soon as any single day risks exceeding 200.
Migrating SMTP setups
Migrating TO SMTP2GO
SMTP2GO is a drop-in replacement for most transactional SMTP hosts. Coming from SendGrid, Mailgun or Postmark, swap three settings in your client: host (mail.smtp2go.com), port (587) and credentials. Verify your domain in parallel by publishing the two CNAMEs alongside your existing DKIM/SPF records, both platforms can coexist during cutover. Run a 10% traffic split for 72 hours to compare bounce rate and open rate in Reporting › Activity before flipping the remainder. Coming from Amazon SES, you gain a friendlier UI and included support at the cost of higher per-email pricing above 100k/month.
Migrating FROM SMTP2GO
The two common exit paths are cost (moving heavy volume to Amazon SES at $0.10 per 1,000) or a shift to API-first sending (Resend, Postmark). Export suppression lists via /suppressions/search so you do not re-mail known bounces on the new provider, every reputable relay honours a CSV import. Keep the SMTP2GO domain verified for 14-30 days after cutover as a hot fallback: leave the CNAMEs in DNS and point a secondary MX/relay at the old credentials in case the new provider hits an outage during ramp-up.
Frequently asked questions
What SMTP server hostname and ports should I use for SMTP2GO?
Point your client at mail.smtp2go.com on port 587 with STARTTLS for the default global endpoint. SMTP2GO also accepts ports 25, 2525, 8025 and 80 for TLS, and 465, 8465 and 443 for SSL wrapping. If you need data residency, use the regional hostnames mail-us.smtp2go.com, mail-eu.smtp2go.com, mail-eu2.smtp2go.com or mail-au.smtp2go.com.
How do I get my SMTP2GO SMTP username and password?
Log in to the SMTP2GO dashboard and open Sending then SMTP Users. Click Add SMTP User and SMTP2GO generates a username plus a one-time-visible password. Use these values in your mail client, not your account login email. Best practice is one SMTP user per environment (production, staging, printers) so a leaked credential can be revoked without breaking every other integration.
Which SMTP ports does SMTP2GO offer when my ISP blocks port 25 or 587?
SMTP2GO documents ports 2525 and 8025 as unblocked fallbacks for TLS/STARTTLS traffic. Port 443 is also available for SSL-wrapped SMTP when both 465 and 8465 are blocked by egress firewalls. These alternate ports are the same relay, there is no throughput penalty for using them.
How do I choose between the global mail.smtp2go.com endpoint and a regional one?
The global endpoint uses anycast routing and is the right default for most workloads. Pick a regional endpoint (mail-us, mail-eu, mail-eu2 or mail-au) when contractual data-residency requirements demand it or when your app is single-region and you want to minimise the network hop. Regional endpoints share the same account, credentials and quotas as the global one.
How do I verify my sending domain with SMTP2GO’s CNAME records?
Add your domain under Sending then Sender Domains and SMTP2GO generates two CNAME records, one for a per-domain Return-Path subdomain (emXXXX.yourdomain.com) and one for the DKIM selector. Publish both in your DNS and click Verify. DNS propagation is usually minutes to a couple of hours. Once verified, DKIM signing and Return-Path handling are automatic for that domain.
How many concurrent SMTP connections and messages per hour does SMTP2GO allow?
SMTP2GO permits up to 40 simultaneous SMTP connections per account and up to 5,000 messages per open connection, with a default sending speed of 200,000 emails per hour. Higher throughput on Premier plans is negotiated with support. If you hit the concurrency cap, keep sockets warm and reuse connections rather than opening a fresh one per message. TLS handshake overhead is where most naive integrations lose throughput.
This review follows our email infrastructure testing methodology. We disclose affiliate relationships in our editorial independence policy.
