SMTP2GO vs Mailgun for agencies sending on behalf of multiple client domains
SMTP2GO — and it's the sub-accounts that decide it. Every paid SMTP2GO plan from the $10/month Starter includes sub-account management, so each client gets an isolated sending reputation and its own reporting. Mailgun's $15 Basic plan supports exactly one custom sending domain; multi-domain (up to 1,000) starts at Foundation, $35/month. The second-order agency problem — proving to a client what happened to their email — goes the same way: SMTP2GO keeps 30 days of reporting on every paid plan, while Mailgun keeps 1 day of logs on Free and Basic and 5 days on Foundation; 30-day logs cost $90/month there (Scale). Mailgun is the right call when one client needs Mailgun-scale infrastructure — 1,000 domains under one roof, a template builder, dedicated IP pools. Disclosure: SMTP2GO pays us a commission and Mailgun pays nothing, but the sub-account and retention gaps are printed on both vendors' pricing pages, not our opinion.
Side-by-side
| SMTP2GO | Mailgun | |
|---|---|---|
| Client separation | Sub-account management included on all paid plans (isolated reputations, per-client structure) | 1 custom sending domain on Free and Basic; 1,000 custom domains from Foundation ($35/mo) |
| Cheapest multi-client setup | Starter — $10/month (or $100/year) for 10,000 emails, sub-accounts included | Foundation — $35/month for 50,000 emails (first month free) |
| Log / reporting retention | 30 days standard on paid plans; extensible to 2 years via add-on (free plan: 5 days) | 1 day on Free and Basic; 5 days on Foundation; 30 days on Scale ($90/mo) |
| Overage | $1 per 1,000 (Starter); $0.85 per 1,000 (Professional) | $1.80 per 1,000 (Basic); from $1.30 per 1,000 (Foundation); from $1.10 per 1,000 (Scale) |
| Dedicated IP | Included on Professional ($75/mo for 100,000 emails) | One included with Foundation (at 100k+) and Scale; additional $59/IP/month |
| Users & keys | Unlimited SMTP users and API keys from Starter | Free: 2 API keys, 1 user; unlimited users from Foundation |
| Deliverability plumbing | All plans: automatic DKIM/SPF, feedback loops, blacklist monitoring, spamtrap detection, TLS/SSL | Email template builder from Foundation; 5,000 email validations on Scale |
| Affiliate program | 20% of all payments for the first 12 months pays | None found as of 2026-07-12 no program |
- Mailgun Basic's single custom domain means every additional client domain forces the $35/month Foundation upgrade — budget for it on day one if you choose Mailgun.
- Client says “where's my invoice email from two weeks ago?” — on Mailgun below Scale, the logs are already gone (1–5 days). SMTP2GO's 30 days covers it.
- SMTP2GO's free plan is rate-limited to 25 emails/hour until your sender domain is verified — verify each client domain before go-live.
Where to sign up
Disclosure: SMTP2GO pays us 20% of your payments for the first 12 months; Mailgun has no affiliate program we could find as of 2026-07-12. The feature gaps cited above come from both vendors' own pricing pages.
FAQ
Why do sub-accounts matter for an agency?
They isolate each client: SMTP2GO's sub-account management (included on all paid plans, from $10/month) gives every client a separate sending reputation and its own reporting, so one client's bad list can't burn the others and you can show each client only their traffic.
How many client domains can Mailgun handle per plan?
1 custom sending domain on Free and Basic ($15/month); the 1,000-domain allowance starts at Foundation, $35/month (per Mailgun's pricing page, accessed 2026-07-12).
How long can I look back in the logs for client debugging?
SMTP2GO: 30 days of reporting standard on paid plans, extensible to 2 years with an add-on. Mailgun: 1 day on Free and Basic, 5 days on Foundation, 30 days only at Scale ($90/month).
What does a dedicated IP cost on each?
SMTP2GO includes one on Professional ($75/month for 100,000 emails). Mailgun includes one with Foundation (at 100k+ volume) and Scale, with additional IPs at $59/IP/month.
Sources
- https://www.smtp2go.com/pricing/ (accessed 2026-07-12)
- https://affiliates.smtp2go.com/ (accessed 2026-07-12)
- https://www.mailgun.com/pricing/ (accessed 2026-07-12)