Three plugins cover the entire category for the WordPress installations that matter: FluentSMTP, WP Mail SMTP, and Post SMTP. The right choice depends on which providers you want to connect to, whether you need OAuth for Google Workspace or Microsoft 365 without paying for it, and whether the site needs the extras (mobile alerting, backup connections, per-plugin routing) that only appear at the top of the category.
For most sites, FluentSMTP is the answer. It is genuinely free, supports every major provider on its base tier, includes Gmail and Microsoft 365 OAuth without a paywall, and has no upsell prompts in the admin UI. Sites that want the most-installed and most-documented option (or that are already running a WPForms/AIOSEO/MonsterInsights stack from Awesome Motive) usually end up on WP Mail SMTP, whose Pro tier unlocks the connectors that its free tier gates behind an upgrade prompt. Sites managing multiple installs from a central console reach for Post SMTP for its mobile alerting and Chrome extension.
FluentSMTP: the strongest free option
Built by WPManageNinja (the FluentForms team) and released as free-forever on wordpress.org. No Pro tier, no upgrade prompt, no gated connectors. The free plugin ships with support for Amazon SES, Google Workspace / Gmail (OAuth), Microsoft 365 / Outlook (OAuth), SendGrid, Mailgun, Postmark, Brevo, Elastic Email, SparkPost, SMTP2GO, and any generic SMTP host.
The features that matter beyond connectivity: per-sender routing (useful for a site that sends transactional through Postmark and marketing through Brevo), a built-in email log with resend, and a fallback connection that fires when the primary provider returns an error.
Where it falls short: the UI is functional rather than polished, the documentation is thinner than WP Mail SMTP’s, and there is no first-party support channel to escalate to when something breaks. The community is smaller. If the site needs Amazon SES SNS webhook handling for bounce/complaint processing, that’s out of scope for the plugin and needs a separate handler.
WP Mail SMTP: the most-installed and most-documented
Owned by Awesome Motive, installed on more than three million sites, and the default when a WordPress site’s first troubleshooting step is to search “wordpress email not sending” and click the first result. The free tier connects to SMTP, Sendinblue/Brevo, Mailgun, SendGrid, SparkPost, Google Workspace/Gmail (OAuth), Postmark, SMTP2GO, and generic SMTP. The Pro tier ($49/year and up, per-site pricing) adds Microsoft 365 / Outlook (OAuth), Amazon SES, Zoho Mail, Sendinblue transactional, plus email logging, email alerts (Slack/Twilio), and one-off tools like the “smart routing” per-condition sender.
The Pro price is easy to justify for a WooCommerce store or a site that treats email as operationally critical: the logging alone is worth the annual fee when a customer emails to say they never received an order confirmation. For a site that doesn’t need those extras, the free tier is fine, but be aware that “Microsoft 365 OAuth” and “Amazon SES” are both behind Pro. If you need either of those and don’t want to pay, use FluentSMTP.
Awesome Motive’s admin UI includes upgrade prompts throughout the plugin. Some operators find these acceptable; others find them intrusive to the point of switching plugins. The prompts are the trade-off for the free tier being as generous as it is.
Post SMTP: the multi-site option
Post SMTP has a smaller install base but a specific audience: sites (and agencies managing multiple sites) that want operational visibility beyond the WordPress admin. The free tier includes a mobile app (iOS/Android) for send notifications and delivery failure alerts, a Chrome extension for cross-site log viewing, and Microsoft 365 OAuth without a paywall.
The connector list is broadly similar to the other two: Amazon SES, Mailgun, SendGrid, Postmark, Brevo, Google Workspace, Microsoft 365, and generic SMTP. Post SMTP’s Pro tier adds AI-driven delivery diagnostics and enterprise multi-site management features that only make sense at agency scale.
For a single site, Post SMTP is a reasonable third option but doesn’t beat FluentSMTP or WP Mail SMTP on either free-tier generosity or admin polish. For an agency running twenty client sites and wanting one console to watch email health across all of them, it becomes more compelling.
The plugins to skip
Several older SMTP plugins remain in the wordpress.org directory but should not be the choice for a new setup in 2026:
- Easy WP SMTP. Ownership has changed several times; a security vulnerability in 2020 (arbitrary file access via debug log) affected 500,000+ installs. The plugin still exists and works, but WP Mail SMTP does the same thing with more active maintenance.
- Configure SMTP and other pre-2020 plugins with fewer than 10,000 active installs. Inactive maintenance, no OAuth support, no encrypted credential storage in most cases.
- Any plugin that stores SMTP passwords in the WordPress database as plaintext. All three plugins recommended above encrypt credentials (or use OAuth, which sidesteps storing a password at all). Plugins that don’t do this (most pre-2020 SMTP plugins) leave credentials exposed to any WordPress admin, any database backup, and any breach that exposes the database.
Choosing between the three
For a site that just needs mail to send reliably and doesn’t want to pay: FluentSMTP.
For a site that treats email as operationally critical, has budget, and values the logging + alerting: WP Mail SMTP Pro.
For an agency managing many client sites from a central console: Post SMTP.
For a Google Workspace or Microsoft 365 sending setup specifically, the OAuth flow matters, and both FluentSMTP (free) and WP Mail SMTP (Google free, Microsoft Pro) handle it cleanly. For Amazon SES specifically, FluentSMTP free or WP Mail SMTP Pro. For most sites, the plugin choice is not the load-bearing decision; the provider choice underneath is. See What is the best way to set up email on WordPress? for the full setup, and transactional email providers for the provider comparison.