WP Mail SMTP vs FluentSMTP vs Optcatch: Which One Do You Need?

1 November 2026 · 6 min read

If you are comparing WP Mail SMTP vs FluentSMTP vs Optcatch, you are probably trying to answer one of two questions: "Why are my WordPress emails not arriving?" or "How do I send a newsletter to the people who filled in my forms?" Those sound similar, because all three plugins touch email, but they solve different problems. This post explains what each one is for, where they overlap, and when it makes sense to run an SMTP plugin and Optcatch side by side.

The short answer

WP Mail SMTP and FluentSMTP are mail-delivery plugins. They take the email WordPress already sends (password resets, order confirmations, form notifications) and route it through a proper SMTP server or email API instead of your web host's default mail function.

Optcatch is an email-marketing plugin. It builds a mailing list from the forms already on your site, stores a consent record for every contact, lets you segment that list, and sends campaigns and newsletters through one or several sending accounts that you connect.

So the question is usually not "which one", but "which job am I trying to do".

What WP Mail SMTP and FluentSMTP do

By default, WordPress sends mail with the wp_mail() function, which on many hosts relies on the server's built-in mail transport. That mail often lacks proper authentication, so it ends up in spam or never arrives. SMTP plugins fix this.

In general terms, both plugins:

• Replace the default transport behind wp_mail() with an authenticated SMTP connection or a provider's email API.
• Let you connect common providers (for example Gmail, Microsoft 365, SendGrid and other transactional services) or any generic SMTP server.
• Offer email logging, so you can see what your site sent and whether it went through.

FluentSMTP is also known for letting you configure multiple connections and set a fallback connection if the primary one fails.

Both are good at what they are built for: making sure the email your site already generates actually gets delivered. Neither is designed to collect subscribers, record consent or run newsletter campaigns. That is not a weakness; it is simply a different job.

What Optcatch does

Optcatch starts one step earlier, at the form. According to its documentation, it:

• Captures leads and records consent. Universal auto-detect picks up the forms you already have (Contact Form 7, WPForms, Elementor, Gravity Forms and more), and by default a consent checkbox is added so unticked submissions are not stored. Each contact keeps a consent basis, wording version and timestamp, and every send is checked against it. See how form capture works. Every email carries a one-click unsubscribe link and List-Unsubscribe headers.
• Segments your list. Filter by source (captured or imported), tag, signup date or consent status; Contact Form 7, WPForms, Elementor Pro Forms and Gravity Forms tag their contacts automatically. CSV import and export are included (up to 5,000 rows per file).
• Sends campaigns. A campaign builder, six starter templates and a drag-and-drop studio for your own templates, plus a delivery dashboard with sent, failed and skipped counts per campaign and per sending account.
• Spreads sending across accounts. You can connect as many sending accounts as you like (Gmail or Google Workspace and Microsoft 365 or Outlook via OAuth2, SendGrid via API, or any SMTP server). Campaigns rotate across them, and each account has its own daily limit and per-minute sending speed. A circuit breaker pauses an account automatically when its provider starts rejecting mail.

All of that is in the free version, which has no limits on contacts, segments or custom templates. Optcatch Pro adds features rather than bigger numbers, such as automatic warm-up, scheduled sends, webhooks and attachments, and you can see the Pro features.

Side-by-side comparison

The SMTP plugin columns describe their general, well-known purpose. Check each plugin's own page for current features and editions.

Can Optcatch replace my SMTP plugin?

Partly, and only if you want it to. Optcatch has a setting called "Use Primary Sending Account for all WordPress email". The in-plugin guide (Optcatch, Guide, step "Send a Test Email & Fix All WordPress Mail") describes it as global mail routing: with the box checked, notifications from every form on your site, store orders, password resets and every other email your site sends are routed through your authenticated primary sending account.

That makes it useful in a few situations:

• You have no SMTP plugin yet and your site mail is unreliable. If you already connected a sending account in Optcatch and confirmed with the test email that it lands in the inbox, enabling this option sends your site mail through that same authenticated account, without adding another plugin.
• You want one place to manage sender accounts on a small site.

Keeping a dedicated SMTP plugin can still be the better choice when:

• You rely on its email logs or other delivery tooling for transactional mail.
• You want transactional mail on a separate connection from your marketing sends, for example a transactional email service for order emails and a regular mailbox for newsletters.
• It already works and you have no reason to change it.

The Optcatch readme says it plainly: you can keep your SMTP plugin for transactional mail. Optcatch's campaign sending works through its own sending accounts either way.

Use one mail-routing plugin at a time

As general advice, let only one plugin take over WordPress's site-wide mail. If you keep WP Mail SMTP or FluentSMTP for transactional email, leave Optcatch's "Use Primary Sending Account for all WordPress email" option unchecked. If you want Optcatch to handle site mail, turn off the other plugin's mailer. Two plugins both trying to reroute wp_mail() make it harder to tell which connection actually sent a given message, and harder to troubleshoot when something does not arrive.

Why not just send newsletters through an SMTP plugin?

You technically could loop through a list and call wp_mail(), but you would be missing the parts that make bulk sending safer and easier to keep compliant:

• Consent. You need to know who agreed to receive marketing email, when, and to what wording. Optcatch stores that and checks it on every send.
• Unsubscribes. Every campaign email needs a working one-click unsubscribe, and unsubscribed contacts must be excluded automatically.
• Pacing. Mailbox providers limit how much a single account can send. Optcatch spreads a campaign over time with a daily limit and sending speed per account, and rotates across several accounts so no single mailbox hits its provider limit.
• New-account reputation. A fresh mailbox that suddenly sends hundreds of emails tends to get flagged. In the free version you raise the daily limit yourself, starting low (for example 50 a day) and raising it over two to four weeks, as the sending accounts guide explains, while Optcatch Pro does that ramp automatically.

Which setup should you choose?

• You only need site emails to arrive: use WP Mail SMTP or FluentSMTP.
• You want to turn form submissions into a consented mailing list and send newsletters: use Optcatch, and keep your SMTP plugin for transactional mail if you already have one.
• You are starting from scratch on a small site and want fewer plugins: use Optcatch for campaigns and consider enabling its "Use Primary Sending Account for all WordPress email" option, as long as no other plugin is routing your mail.

You can install the free version from the Optcatch plugin page on WordPress.org, follow the getting started guide, and try it alongside your current SMTP setup.

Read next

• Capture Contact Form 7 Leads into a Newsletter List
• GDPR Mailing List in WordPress: Consent & Unsubscribe
• Send Newsletters from WordPress with Gmail or Microsoft 365