Comparison
This is the rare comparison where price decides nothing: both plugins are genuinely, entirely free. The differences live elsewhere, in why each one is free, in what each one considers its job, and in where your credentials travel. Every claim about FluentSMTP below comes from their own site, documentation or listing, checked on 30 July 2026 and linked at the bottom.
01 · Common ground
More is identical here than in any other comparison on this site, starting with the one thing most SMTP plugins gate: the price of the useful parts.
02 · The split
Neither gratuity is a trick. But they are not the same gratuity, and the difference shapes both plugins.
FluentSMTP is free the way a well-built lobby is free: it belongs to a house. WPManageNinja says so themselves, on the page where they explain the choice: the plugin was built because their own paid products, Fluent Forms, FluentCRM, FluentBooking, needed reliable delivery, and it doubles as a contribution to the ecosystem their customers live in. That is a legitimate model, executed generously, and the plugin gates nothing.
Custom SMTP is free because it is the entire offer of a solo maintainer: there is no suite behind it, no other product it leads to, and nothing else it needs to serve. The visible consequence is scope. FluentSMTP is also infrastructure for marketing email, with several simultaneous connections, per-sender routing, a fallback connection and reporting dashboards; Custom SMTP covers transactional sending, its log and its alerts, and deliberately stops there.
03 · Side by side
Everything in both columns is free; the differences are in coverage, not in price. Sources for every row are at the bottom of the page.
| FluentSMTP | Custom SMTP | |
|---|---|---|
| Send through your provider | 15+ connections, SMTP and APIs | 12 presets + any SMTP server |
| Amazon SES | Access key + secret key, stored in the database or wp-config | API with IAM role, no stored keys |
| Gmail / Google Workspace | OAuth API: create your own Google Cloud app, authorization redirects via fluentsmtp.com | SMTP with an app password, no third party in the flow |
| Email log, resend | Log, resend, reporting dashboard | Log, preview, resend, CSV export |
| Failure notifications | Email, Slack, Telegram, Discord | Email, webhook, admin notice |
| Volume-spike alerts | Not advertised | Absolute hourly and daily thresholds |
| Multiple connections, routing, fallback | Several providers at once, per-sender routing, fallback connection | Not offered |
| WordPress notification switches | Not advertised | Free, one switch per email |
| Settings locked in code | Credentials via wp-config constants | Every setting, PHP constants and environment variables |
| WordPress 7.0 | Tested up to 6.9.5; last release December 2025 | Tested up to 7.0, PHPMailer 7.0.2 |
| Price | Free, pledged never monetised | Free, no paid version |
A nuance that cuts their way on Outlook: their Microsoft connection uses the OAuth API, which is not affected by Microsoft’s staged retirement of basic SMTP authentication; our Outlook preset is SMTP and is. The Outlook guide documents that timeline.
04 · Credit where due
An honest comparison has this section, and not as a formality. If these points decide it for you, take their plugin.
05 · The other side
The same standard applies in this direction: each point is verifiable, in the code or on the screen.
06 · The short version
Two sentences each, no hedging.
Take FluentSMTP if you run several providers at once, want routing and a fallback connection, prefer OAuth API sending for Gmail or Outlook, want Telegram or Discord alerts without wiring a webhook, or already live in the Fluent suite. It is genuinely free and their pledge is public.
Take Custom SMTP if you want one provider configured plainly over SMTP, Amazon SES with no stored keys, every setting forceable from code, spike alerts as well as failure alerts, the WordPress notification switches, and a plugin with no ecosystem attached, in English and in French. That is the whole offer.
Install, pick your provider from the preset list, send yourself a test. The twelve guides carry the exact values, provider by provider.
Same method, same standard: against WP Mail SMTP and against Post SMTP, every claim sourced on their own pages and dated.
Sources, all checked on 30 July 2026: the FluentSMTP site (“Free Forever”, connections, fallback, notification channels, reporting), their “why is it free” page (built for their product suite), their Amazon SES documentation (access key and secret key, storage), their Gmail documentation (Google Cloud app, fluentsmtp.com/gapi/ redirect URI) and the FluentSMTP listing on WordPress.org (installations, reviews, never-monetize pledge, tested-up-to and last release). Facts about Custom SMTP are verifiable in its public code. Found something outdated? Say so on the support forum and this page gets fixed.