Three plugins do the WordPress SMTP-relay job competently. Each has a distinct philosophy and a distinct failure mode, and the right choice depends less on a feature checklist than on what kind of operator is installing it. This piece names the three by use case, then explains why the recommendation lands where it does.
The verdict
For most operators installing their first WordPress mailer plugin: WP Mail SMTP. The setup wizard is the most polished in the category, 15 mailer integrations ship in the free version, and the four-million-install base means edge-case bugs find their way to the issue tracker faster than anywhere else. The Pro tier ($99/year on renewal, $49 first year, single site) adds logging and routing; the free version handles the core SMTP job.
For operators who want logging and routing in the free version, or who do not want their admin area pushing upgrades: FluentSMTP. Built by WPManageNinja as an open-source alternative to the freemium pattern, FluentSMTP includes email logging, resend, fallback servers, and Amazon SES support without a paid tier. It assumes a reader comfortable with finding settings without a wizard hand-holding them through.
For operators who care about being told when delivery fails, on the channel they actually watch: Post SMTP. Push notifications to Chrome, Slack, and Twilio SMS make Post SMTP the only plugin in the category whose first-class feature is “tell the operator when something is wrong.” Logging, OAuth, and a resend-from-log button ship in the free version.
Each recommendation has a case where it is wrong, named in the relevant section below. The four lesser plugins worth knowing about (Easy WP SMTP, SMTP Mailer, Gmail SMTP, YaySMTP) sit lower for the reasons listed under “Honourable mentions.”
How we read the field
This is a documentation-and-source comparison. The claims about each plugin’s free vs paid feature split, mailer support, install counts, and pricing are taken from each plugin’s wordpress.org page, the vendor’s own pricing page, and the readme.txt in the plugin source. Where a claim depends on hands-on UX evaluation (setup-wizard quality, error-message clarity, the polish of the admin interface), it is stated as such. A follow-up piece with side-by-side test sends from a clean WordPress install is scheduled.
Versions, install counts, and pricing referenced here are current as of 2026-06-11. Plugin versions tested against: WP Mail SMTP 4.8.0, FluentSMTP 2.2.95, Post SMTP 3.9.4. WP Mail SMTP’s published prices include a $50 first-year discount; renewal prices are cited throughout this piece as the steady-state cost.
For context on the underlying SMTP relays these plugins front for, see the SMTP services directory. For the no-plugin path (using wp_mail() filters directly), see WordPress SMTP without a plugin.
WP Mail SMTP
WP Mail SMTP, by Awesome Motive (the WPForms / OptinMonster / MonsterInsights group), is the category’s incumbent: 4 million-plus active installations and a setup wizard that gets non-technical users through the configuration the first time. Among the three contenders, it is the only one with that wizard, and the wizard is the reason it is the typical first install on agency-managed client sites.
The 15 free mailers cover the providers most WordPress operators reach for: SendLayer, SMTP.com, Brevo, Gmail and Google Workspace (via OAuth), Elastic Email, Mailgun, Mailjet, SendGrid, Postmark, SparkPost, SMTP2GO, Resend, Mandrill, MailerSend, plus a generic “Other SMTP” option. Three integrations are gated behind Pro: Microsoft 365 / Outlook, Amazon SES, and Zoho Mail. If the operator’s chosen relay is one of those three, the Pro tier ($99/year on renewal) becomes a hard requirement, not an optional add.
The free version also covers a From-name and From-email override, which forces a single sender identity across every email WordPress sends regardless of the originating plugin. This is one of those small features that prevents a recurring deliverability problem (plugin authors hardcoding their own From addresses, breaking DMARC alignment) and is the kind of thing operators only realise they wanted after the first time it bites them.
What sits behind Pro. The Pro tier (single site, $99/year on renewal) adds email logging, weekly email reports, backup connections (automatic fallback to a second mailer if the primary fails), smart routing (conditional logic to send different emails through different mailers), rate limiting, background queue processing, multisite settings, and failure alerts via Slack / Teams / Discord / SMS / webhook. The three Pro-only mailers (M365, SES, Zoho) sit here too. Resend-from-log lives in the Pro tier, since the log itself is Pro-only.
Higher tiers: Elite ($149/year on renewal) adds White Glove Setup. Developer ($249/year on renewal) covers 20 sites. Agency ($449/year on renewal) covers 100 sites. Every tier has a $50 first-year discount; the renewal is the long-term price.
| Tier | Sites | First year | Renewal |
|---|---|---|---|
| Pro | 1 | $49 | $99/yr |
| Elite | 5 | $99 | $149/yr |
| Developer | 20 | $199 | $249/yr |
| Agency | 100 | $399 | $449/yr |
The single feature most operators reach for after the initial mailer configuration is email logging. WP Mail SMTP gates it behind Pro. This is the line that ends a lot of “should I stay free?” conversations: for operators who need to know whether a specific email actually left WordPress, the choice is paying for WP Mail SMTP Pro or installing FluentSMTP or Post SMTP, both of which log in their free tiers. The plugin you regret a year in is usually the one that did not log. That decision happens at install time.
Where WP Mail SMTP is the wrong choice. Agencies running 20+ client sites on the Developer tier ($249/year on renewal) are not getting a different plugin than what the Pro tier offers; they are paying for the site count. If the agency’s relay is something other than Microsoft 365, Amazon SES, or Zoho, the free FluentSMTP plugin covers the same functional ground without the per-site licence. Operators who object on principle to admin-area upgrade prompts are not going to enjoy WP Mail SMTP; the upsell messaging is persistent, by Awesome Motive’s house style, and not configurable away.
The plugin’s reach and the wizard make it nanoPost’s default for first-time installs and for client estates where the operator who configures the plugin is not the operator who will troubleshoot it six months later. For everyone else, the next two contenders are worth considering before defaulting.
FluentSMTP
FluentSMTP, by WPManageNinja, is the open-source answer to the freemium pattern. 600,000-plus active installations, version 2.2.95, and a published philosophy that the plugin should be free and feature-complete rather than a funnel into a paid tier. There is no FluentSMTP Pro; the vendor’s commercial work sits in adjacent products (Fluent Forms, FluentCRM), and the SMTP plugin is the free anchor. The result is the plugin most aligned with what an operator coming from outside the WordPress commercial-plugin culture expects: install, configure, done, no upgrade prompts in the dashboard.
The free version includes multiple SMTP connections (run two relays at once and route specific From addresses through each), fallback server support (if the primary connection fails, the next one tries), email logging with resend, and API-based integrations for the providers that offer one. Coverage includes Amazon SES (which WP Mail SMTP gates behind Pro), Mailgun, SendGrid, Brevo, Postmark, SparkPost, SMTP2GO, Mailjet, and the generic SMTP option. Gmail and Microsoft 365 via OAuth are also covered in the free plugin.
The connection-routing feature is the closest thing this category has to a unique capability. An operator running a WooCommerce store can route transactional order confirmations through Postmark (where deliverability is the priority) while routing marketing newsletters through SendGrid (where price-per-message at volume is the priority), and the routing logic lives inside FluentSMTP. WP Mail SMTP offers “Smart Routing” in Pro for the same purpose; FluentSMTP includes it free.
Where FluentSMTP is the wrong choice. The setup is more terse than WP Mail SMTP’s wizard. An operator who has never configured SMTP credentials and does not understand the difference between port 587 STARTTLS and port 465 SSL will get further faster with WP Mail SMTP’s guided flow. FluentSMTP assumes a reader who can pair a relay’s docs with the plugin’s connection form without intermediation. Most professional WordPress operators clear that bar; first-time users may not.
The plugin’s documentation, while serviceable, is thinner than WP Mail SMTP’s. Mailer-specific quirks (SES sandbox-mode behaviour, M365 SMTP AUTH timeline, Postmark’s broadcast vs transactional split) are not addressed in FluentSMTP’s docs the way they are in WP Mail SMTP’s knowledge base. For these, the operator is reading the relay’s own documentation, which is usually where the answer lives anyway.
The plugin is nanoPost’s recommendation for operators who want logging, resend, and routing without a per-site licence, who are comfortable configuring SMTP without a wizard, and who object to admin-area upgrade pressure as a matter of taste.
Post SMTP
Post SMTP, by WPExperts, has the longest lineage of the three. It started life as Postman SMTP, was rebranded and taken over by its current maintainers, and has been actively developed since. 300,000-plus active installations, version 3.9.4, and a feature posture that emphasises one capability the other two do not match.
That capability is failure notification. Post SMTP is the only plugin in the category whose free version pushes notifications to Chrome (browser push), Slack, and Twilio SMS when an email fails to send. For an operator running a WooCommerce store, this is the difference between hearing about a broken order-confirmation email at 2 PM via the user complaint and hearing about it at 8 AM via Slack while it is still recoverable. WP Mail SMTP offers email failure alerts in Pro; Post SMTP includes them free. Microsoft Teams alerts are a Pro addition.
The free version also includes OAuth 2.0 (the same path WP Mail SMTP charges for in the M365 case), built-in email logging with a resend button, a configuration wizard that auto-detects common SMTP settings from the entered hostname, custom Reply-To / Cc / Bcc configuration, and a fallback SMTP service for when the primary fails. FluentSMTP and WP Mail SMTP Pro both log and resend; Post SMTP’s distinguishing addition is the push-channel alert, free.
What sits behind Pro. Post SMTP restructured its commercial offering in the last two years; what was previously a constellation of per-extension purchases ($30-100 per extension) is now Post SMTP Pro, a single subscription. The Pro tier adds the M365, Amazon SES, and Zoho Mail premium SMTP integrations (the same three that WP Mail SMTP also gates), advanced logging, email open-tracking, and additional alert channels (Microsoft Teams, webhook). Pricing varies by site count and is published on the 
Post SMTP pricing page.
Where Post SMTP is the wrong choice. The admin interface, while functional, is the least polished of the three. The plugin shows its age in places where WP Mail SMTP and FluentSMTP have had design refreshes Post SMTP has not. Operators who prioritise interface polish over feature coverage will notice. The mobile app for delivery alerts is a real feature but the experience is closer to a utility than a product; the operator who is going to actually look at the app is the operator who already wanted the alerts.
The changelog is more visibly that of a small team than of the larger plugins’ release cadences. Recent versions have included fixes for socket-related errors and PHP-version compatibility issues that most operators will never see, but the fix-and-react pattern is closer to the surface than in WP Mail SMTP or FluentSMTP.
Post SMTP is nanoPost’s recommendation specifically for operators who run WooCommerce, membership, or LMS sites where transactional email delivery is operational rather than incidental: sites where being told about a failure in real time has commercial consequences. For sites where the operator will only ever check email logging if a user complains, the failure-notification advantage is not earning its keep.
Honourable mentions
These four plugins are installed on enough WordPress sites to warrant mention. None is the recommendation for an operator still choosing; each works for the operators who chose it.
Easy WP SMTP (now maintained by the WP Mail SMTP team under Awesome Motive; 500,000-plus installs) overlaps almost entirely with WP Mail SMTP’s free tier and is under the same parent. The two plugins exist because of acquisition history; the practical implication is that an operator already using SendLayer (the SMTP service the same group operates) will find slightly tighter integration in Easy WP SMTP than in WP Mail SMTP, but for any other relay, WP Mail SMTP is a more complete free plugin.
SMTP Mailer (by naa986; 70,000-plus installs) is a deliberately minimal plugin: SMTP credentials, From override, test send. No logging, no failure alerts, no Pro tier. For an operator who wants exactly that and nothing else, it works. For an operator who will want logging two weeks later, it is the wrong starting point.
Gmail SMTP (by naa986, same author; 10,000-plus installs) is SMTP Mailer scoped specifically to Gmail with the OAuth flow built in. It predates WP Mail SMTP’s native Gmail OAuth integration and has not added a reason to choose it over the larger plugins since.
YaySMTP (10,000-plus installs) is a newer entrant with a clean interface and SMTP-and-API support, including some providers the larger plugins have been slow to add. For operators using Maileroo, MailerSend, or a similarly recent provider, YaySMTP is sometimes the path of least resistance. For the established providers, the larger plugins have more mature support.
Choosing for your situation
You are configuring SMTP on a single WordPress site for the first time. Use WP Mail SMTP. The setup wizard is the reason. The free tier covers your relay unless your relay is M365, SES, or Zoho. If it is one of those three, install FluentSMTP or pay for WP Mail SMTP Pro.
You manage WordPress for clients and want a free plugin that does not push upgrades in the dashboard. Use FluentSMTP. The interface stays out of the way, logging and routing are free, and the operator who inherits the site after you leave will not get nagged into a paid plan they do not need.
You run a WooCommerce store, membership site, or LMS where email delivery has commercial consequences. Use Post SMTP and configure the failure notifications. Logging is necessary; being told in real time when delivery fails is necessary.
You are choosing an SMTP relay and have not yet picked a plugin. The relay decision matters more than the plugin decision. See the SMTP services directory and the relay-specific guides (Gmail OAuth vs App Passwords, Amazon SES setup, Postmark review) before locking the plugin in.
What we did not test
This piece is a documentation and source comparison. The following are real questions that a hands-on test would answer, and that this piece does not:
- Side-by-side comparison of the error UI when each plugin is given deliberately broken credentials. The plugin that surfaces “auth failed at smtp.host.com because port 587 is blocked” is a meaningfully different product from the one that surfaces “Mailer failed to start.”
- The actual feel of Post SMTP’s failure-notification flow under real-world conditions: does Chrome push survive an extended browser-closed window, does Slack post arrive within minutes of the failure, does the alert clear when the next send succeeds.
- Behaviour on OAuth token refresh failures, DNS resolution timeouts, and TLS-handshake errors. These are the failure modes most operators actually encounter; the documentation rarely covers what the plugin does with them.
- Pro-only features without a trial. WP Mail SMTP Pro’s smart routing, Post SMTP Pro’s open tracking: not covered here from hands-on use.
- Multi-site network installs. WordPress multisite changes the surface for each plugin and is its own piece.
- Plugin behaviour under WP-CLI, headless, or REST-API contexts where the admin interface is not the surface. Some failures are admin-only.
These belong in a follow-up testing piece. The recommendation here stands on documented features and the existing nanoPost individual reviews; the testing piece will adjust the verdict where hands-on contradicts the documentation.