Inbox Monster vs SMTP Labs
Inbox Monster
inboxmonster.comSMTP Labs
smtp.devSide by side
| Figure | Inbox Monster | SMTP Labs |
|---|---|---|
| Price from | $312.50/mo | $7/mo |
| Free plan | — | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| API | — | Yes |
| Plans published | 5 | 3 |
| Spec score · Email Testing Software | 7.6 (#20) | 8.4 (#8) |
| Integrations | Documented integrations include Salesforce Marketing Cloud, Braze, Iterable, SparkPost, Twilio SendGrid and Amazon SES. | The maker documents CI use with GitHub Actions, Jenkins, GitLab CI, and CircleCI, using standard SMTP and the REST API. |
| Purpose | Inbox Monster provides tooling for creative rendering, inbox intelligence and email deliverability for global email teams. | SMTP Labs is an email testing service that receives test email over SMTP and lets users inspect it through the web UI, IMAP, POP3, or API. |
| Security controls | The Trust Center lists audit logging, data security, multifactor authentication, penetration testing and encryption-at-rest documentation. | The privacy policy says the service uses encryption, firewalls, SSL technology, and third-party authentication protections. |
Plans
Inbox Monster
- Essential (Creative suite)$3,750 a year
- SMS suite$6,000 a year
- Advanced (Creative suite)$6,500 a year
- Enterprise (Creative suite)$10,000 a year
- Deliverability suite$15,000 a year
In their own words
Inbox Monster
Inbox Monster has no write-up on Specifiction yet; its figures are above.
SMTP Labs
SMTP Labs is an email testing service that receives test messages over SMTP and lets you inspect them on the web, through IMAP or POP3, or via an API. Messages remain in a sandbox and cannot reach external recipients. Inspection includes HTML and plain text, headers, MIME structure, raw source, and attachments. SPF, DKIM, and DMARC checks appear in the interface and API, while a deliverability audit reviews sender configuration, HTML, links, and content patterns associated with spam filters. The REST API covers domains, accounts, mailboxes, messages, and tokens; server-sent events can push new messages. SMTP, IMAP, and POP3 work without a vendor SDK. The Lite plan is free at free with one domain, 50 accounts, and seven-day retention. Pro costs $7 a month, and Max costs $20 a month, with longer retention and expanded domains or accounts. Email and account data are primarily processed in the United States.