Evidence, with its limits.

What this collection covers

Third-party services for sending application email, including transactional platforms, cloud infrastructure, SMTP delivery and platforms that also handle campaigns. This first collection is not an exhaustive market census. Personal inbox hosting and development libraries are outside its current scope.

Price is more than one number

Monthly subscriptions, prepaid credits and usage-based rates are shown with their units. A selected plan is not automatically the cheapest plan for your workload. Check recipients, daily limits, attachment data, region, taxes, dedicated IPs and unused-credit expiry before estimating your bill. A temporary trial is not a permanent free tier.

Where official pages are incomplete or contradictory, we leave the rate unverified instead of guessing. We do not calculate a universal cheapest-provider ranking from unlike prices.

Reliability: three different questions

• Contractual SLA: what the provider commits to, under its eligibility, exclusions and credit rules.
• Incident history: provider-reported events on an official status page. A broad cloud status page may cover more than email.
• Observed performance: independently measured availability, delivery latency and inbox placement over a stated period. We do not yet have a consistent cross-provider test dataset.

We therefore show “Not measured” for observed results. An SLA percentage is not a measured delivery rate, and a missing status link does not imply poor reliability.

Features and unknowns

“Available” means the source documents the feature, not that every plan includes it. Unconfirmed attributes distinguish values not stated in reviewed documents, conflicting sources and unreadable current materials. Expand Review details for the reason, date and checked sources. None means “No.” Cells retain plan details whenever verified. Difference filtering compares the displayed descriptions; it is a reading aid, not a feature-equivalence test.

Sources and updates

Each documented fact links to its official source and is stored with a review date. Editorial fit and trade-off notes interpret those facts and are not hands-on reviews. Recheck official terms before purchasing. Data is a dated snapshot, not live monitoring.