Install the 
official MailerSend SMTP integration if the site has already settled on MailerSend and wants a single-purpose plugin that does one thing. Install a general mailer plugin with a native MailerSend mailer, such as WP Mail SMTP or Post SMTP, if the host blocks outbound SMTP or the site might change providers later. A site that needs free routing by from-address should install FluentSMTP. The official plugin and FluentSMTP reach smtp.mailersend.net:587 with an SMTP credential pair. The native mailers reach api.mailersend.com over HTTPS with an API token. The native mailers count each send as one API request against MailerSend’s daily quota, which is 100 on the free tier; SMTP relay also uses that quota, though the number of requests can vary with the SMTP client’s sending method.
For the case for or against MailerSend as the sending service (the 500-a-month free tier with vendor branding, the $7 Hobby tier for small sites, the crossover with SMTP2GO at the low end), start at the MailerSend review. This page is the setup walk-through. It assumes the decision to use MailerSend has already been made.
Which plugin to install
Six plugins reach MailerSend. The vendor’s plugin and FluentSMTP connect over SMTP. WP Mail SMTP, Post SMTP, Easy WP SMTP and Meow Mailer ship a native mailer that uses MailerSend’s API on port 443. The choice comes down to which port the host leaves open, and whether the operator wants a minimal, MailerSend-only integration or a general-purpose mailer plugin.
MailerSend Official SMTP Integration is the vendor’s own plugin, published by MailerSend and last tested against WordPress 6.9. It exposes one settings screen: paste the SMTP username, paste the password, set the from-address, save. The plugin does not ship email logging, fallback, or routing – it hands the send off to smtp.mailersend.net and returns whatever the SMTP server said. Pick it when MailerSend is the final decision, when a second mailer plugin’s feature set is not needed, and when the operator prefers the smallest possible install on the WordPress side.
WP Mail SMTP has a native MailerSend mailer in the free plugin. It sends through MailerSend’s API with an API token, so a host that blocks outbound SMTP does not stop it. The free plugin adds a setup wizard; email logging, backup connections and smart routing are on the Pro tier. Its Other SMTP option still connects to smtp.mailersend.net:587 for a site that prefers SMTP credentials. Pick it when the site might change providers later, or when the operator expects to buy Pro for logging and routing.
FluentSMTP has no MailerSend provider as of version 2.4.5, so it reaches MailerSend through its SMTP Server connection on smtp.mailersend.net:587. FluentSMTP is free and open-source with no upsell path, and it picks a connection by from-address, where WP Mail SMTP keeps routing for Pro. Pick it when the site runs multiple senders and needs per-address routing without paying for WP Mail SMTP Pro.
Post SMTP has a native MailerSend mailer in the free plugin, sends to api.mailersend.com with an API token, and keeps its email log free. Its differentiator is real-time failure notifications (Chrome push, Slack, Teams, and SMS on the paid tier); if a bounced order confirmation needs to page an operator within minutes, Post SMTP is the plugin.
Easy WP SMTP has the same native mailer in its free plugin, although its readme’s mailer list leaves MailerSend out. Logging, alerts, a backup connection and routing are Pro features, as in WP Mail SMTP.
Meow Mailer also has a native mailer. There is no Pro tier, so the email log and the fallback provider are free. Per-address routing is not available, because the plugin sends through one provider at a time.
For the plugin-by-plugin comparison in the general case (not MailerSend-specific), see best WordPress SMTP plugins.
Before touching WordPress
MailerSend will not accept a send from a domain until the domain is added, verified, and its DKIM records propagate. Two things sit upstream of the WordPress install: a verified sending domain, and SMTP credentials generated inside MailerSend’s dashboard.
A new account also starts with limits. 
Sandbox mode sends to 2 recipients until MailerSend approves the account, which can take up to 48 hours. The 14-day Professional trial needs a payment method, which MailerSend verifies and does not charge. The test domain every new account gets is limited to 2 recipients on the trial as well as in Sandbox. The MailerSend review has the routes and what each one allows.
Verify the sending domain and publish DKIM and SPF
Log in to the MailerSend dashboard, then Email > Domains > Add a domain. Enter the domain the WordPress site sends From:, meaning example.com, not mail.example.com. MailerSend returns the DNS records to publish: two DKIM CNAME records under ms1._domainkey.<your-domain> and ms2._domainkey.<your-domain> pointing at MailerSend’s key servers, one CNAME at mta.<your-domain> pointing at mailersend.net for the return path, an SPF entry to add, and an optional custom tracking CNAME if the site wants tracked links to resolve under its own subdomain.
The SPF entry adds include:_spf.mailersend.net to the domain’s existing SPF record at the apex. If the domain already has an SPF record covering Google Workspace or another sender, edit it to add the include; do not create a second SPF record at the apex, because a domain with two SPF records at the same name is a permanent SPF error under RFC 7208 regardless of what the records say. If the domain has no SPF record, publish v=spf1 include:_spf.mailersend.net -all. The SPF merger folds the MailerSend include into an existing string and counts the DNS lookups against RFC 7208’s ten-lookup ceiling before you publish.
Return to the MailerSend dashboard and click Verify. Verification is typically minutes when propagation is fast and up to an hour on slow DNS hosts. The dashboard reports each record’s status individually; all four (SPF, both DKIM CNAMEs, the return-path CNAME) must show verified before MailerSend signs sends from that domain with DKIM.
DMARC is not MailerSend-specific but is required for domains sending more than 5,000 messages per day to Gmail or Yahoo under their 2024 bulk-sender rules. Publish _dmarc.example.com as TXT v=DMARC1; p=none; rua=mailto:[email protected] as a safe starting point; tighten to p=quarantine or p=reject once reports show no legitimate mail failing alignment. MailerSend’s Starter plan includes 30 days of DMARC monitoring inside the dashboard, and Professional keeps it running longer; the bulk sender authentication checklist has the full order of operations.
Once DKIM and SPF verify in the MailerSend dashboard, the DNS auth checker reads how the MailerSend CNAMEs and the apex SPF resolve from a receiver’s perspective, which catches nameserver caches and mistyped selectors before real traffic does.
Generate SMTP credentials
In the MailerSend dashboard, Email > Domains > pick the verified domain > Manage. Scroll to the SMTP section and click Generate new user. The dashboard displays a username and password once, at creation – copy both immediately, because MailerSend does not show the password again after the modal closes. MailerSend’s SMTP credentials are not scoped to a single domain; they authenticate account-wide and can send from any domain the account has verified.
For the API path (a native mailer in WP Mail SMTP, Post SMTP, Easy WP SMTP or Meow Mailer, or a custom integration), the equivalent step is Email > API tokens > Create new token. API tokens can be scoped per-domain with a permission set. The setup docs for WP Mail SMTP, Post SMTP and Easy WP SMTP all ask for sending access and no more. A native mailer needs only the token, so a site on that path can skip the SMTP user.
Installing and configuring the official MailerSend plugin
The plugin install is standard: Plugins > Add New > search MailerSend > Install > Activate. Deactivate any other mailer plugin still active on the site before enabling MailerSend’s – two mailer plugins overriding wp_mail() at once is the most common cause of an install appearing to do nothing.
In the MailerSend settings screen, four fields matter. Paste the SMTP username generated earlier into SMTP User. Paste the SMTP password into SMTP Password; the plugin stores the password in the WordPress database, so a hosting environment with database access in a shared context should treat that the same way it treats any other API credential. Set From Email to an address at the domain verified with MailerSend, which sends only from addresses at a verified domain. Set From Name to the site or brand name.
Save. The plugin does not run a validate-connection check on save; the test-send button below is the confirmation.
Send a test message to an address you can read. The plugin round-trips the send through MailerSend’s SMTP server and reports success or the SMTP error in the admin. A success reply confirms the credentials, sender identity, and outbound port 587 are wired up correctly; verify the message actually arrived at the destination before treating the setup as done, and open the message headers to confirm Authentication-Results shows dkim=pass for ms1._domainkey.<your-domain> and spf=pass for the sending IP. If either fails, the DNS records did not propagate or were entered incorrectly at the DNS host; return to the MailerSend dashboard’s domain page and re-check.
For a native mailer, select MailerSend in the plugin’s mailer list, paste the API token, set the from-address at the verified domain and save. WP Mail SMTP and Easy WP SMTP also show a Professional Plan toggle, which passes custom headers through to MailerSend. MailerSend’s API limits custom headers to Professional and Enterprise accounts, so leave the toggle off on a lower plan. WP Mail SMTP’s Email Test tab handles the test send.
For SMTP in WP Mail SMTP, the settings live under WP Mail SMTP > Settings > Mailer > Other SMTP. Host smtp.mailersend.net, Port 587, Encryption STARTTLS, Authentication PLAIN or LOGIN, Username and Password from the MailerSend dashboard. FluentSMTP’s SMTP Server connection takes the same field values.
Sending the first test and reading the failure
The three error patterns worth naming.
535 5.7.8 Authentication credentials invalid. The SMTP username or password was mistyped, was regenerated in the dashboard after the plugin saved, or was pasted with a leading space. Copy the credentials again from the MailerSend dashboard (Domains > Manage > SMTP) and paste them into the plugin. If MailerSend does not show the password (only the username), the credential was generated in a previous session and the password is no longer retrievable; delete that SMTP user and generate a new one.
554 The from header is missing or invalid or a sender-verification failure. The from-address is at a domain MailerSend has not verified, or the DKIM CNAMEs have not propagated. Check the MailerSend dashboard’s domain page shows all records verified for the exact domain in the from-address. [email protected] is a different domain to [email protected] under DKIM alignment rules; verify the domain the site actually sends from, not the domain the site is hosted at.
Connection timeouts or SMTP connect errors. The WordPress host blocks outbound port 587. Some shared hosts block outbound SMTP by default and require a support ticket to open it; some managed WordPress hosts (Kinsta, WP Engine) permit outbound SMTP but log traffic separately. If port 587 is blocked and the host will not open it, MailerSend can stay: generate an API token, switch to the native MailerSend mailer in WP Mail SMTP, Post SMTP, Easy WP SMTP or Meow Mailer, and send the test again. Those mailers use HTTPS on port 443.
The MailerSend Activity feed under Email > Activity shows every send in near-real-time with delivery, opens, and any bounce or complaint reason. Point it at the last hour and the test sends appear near the top; a message that shows Delivered in the Activity feed but has not arrived at the destination is a receiver-side delivery decision, not a MailerSend problem, and the message headers (Authentication-Results, Received-SPF) are where the reason lives.
MailerSend-specific things to know
The MailerSend footer stays on messages until Starter. The free 500-a-month tier and the $7 Hobby tier both stamp a MailerSend footer onto every outgoing message. That footer only removes on Starter ($35/month for 50,000 emails). Sites that are running a real customer touchpoint – order confirmations, receipts, password resets that the site’s brand appears on – should size the plan to at least Starter, or accept the vendor branding as a cost of the free tier.
Log retention is short below Professional. The Activity feed retains one day on Free and Hobby, seven days on Starter, and thirty days on Professional. Sites that need longer retention should either mirror sends to a WordPress email log (Check & Log Email, Log Emails, or WP Mail SMTP Pro’s log) in parallel, or plan for Professional.
MailerSend stores its data in the EU by default, so there is no region setting to pick. The company is MailerSend, Inc. of New York, and its privacy policy documents transfers to the US under the Data Privacy Framework. A domain with an EU-resident data policy (a GDPR-focused nonprofit, some public-sector sites) is covered on where the data sits; a policy that rules out a US company should look at an EU-owned provider such as Mailjet or Brevo.
The dedicated IP tier starts at Professional as an add-on, not on Starter. A site on Starter cannot buy a dedicated IP without upgrading. As with any provider, a dedicated IP is worth the money only when the monthly volume clears the roughly 50,000-message threshold below which the IP has too little traffic to build its own reputation.
MailerSend’s free tier caps API requests at 100 per day, separately from the 500-message monthly cap. Every request counts, including each send through a native mailer, so 100 messages a day is the ceiling on that path, and reading the Activity feed or send status through the API spends the same allowance. Hobby raises the quota to 1,000 a day and Starter to 100,000. It resets at midnight UTC. MailerSend’s daily request quota applies to API requests and SMTP relay messages. Each individual SMTP message counts against the quota, so SMTP does not avoid the daily limit.
When another provider fits better
If the priority is the cheapest free tier that ships without vendor branding, SMTP2GO at 1,000 messages a month with no footer fits better than MailerSend’s 500-with-branding. If the site is on the AWS side of the fence and cost per message dominates the decision, Amazon SES at $0.10 per 1,000 messages on opt-in à la carte pricing is cheaper than MailerSend at every tier. If deliverability at high volume is the priority and the budget supports the price step, Postmark is purpose-built for that. If the site’s data policy rules out a US company, Mailjet fits where MailerSend, Inc. does not. The SMTP cost calculator runs the crossover math against a site’s actual monthly send volume.
Related
When you are ready to go further:
- MailerSend review covers the case for and against MailerSend as a sending service, the pricing tiers, and the DNS reference.
- WP Mail SMTP review is the general-purpose mailer plugin, worth pairing with MailerSend when the host blocks SMTP or Pro’s logging and routing matter.
- FluentSMTP review is the free, open-source alternative with routing by from-address.
- Best WordPress SMTP plugins is the general-purpose plugin comparison, not MailerSend-specific.
- WordPress email setup guide places MailerSend inside the wider WordPress email stack.
Corrections
- 2026-11-05: an earlier version said domain setup unlocks MailerSend’s free tier. That plan needs an approved account and a card on file.
- 2026-11-05: an earlier version said the WP mail config generator returned the SMTP credential block for the plugin fields. The generator does not cover MailerSend.
- 2026-11-05: an earlier version said WP Mail SMTP has no MailerSend mailer, that its API path needs Pro, that its email logging is free, that Post SMTP connects over generic SMTP, that a blocked port 587 means changing provider, and that SMTP sends do not touch MailerSend’s daily request cap. WP Mail SMTP, Post SMTP, Easy WP SMTP and Meow Mailer all ship a native MailerSend mailer over HTTPS, and WP Mail SMTP’s logging is a Pro feature. The daily quota covers SMTP messages as well as API requests. The closing section of that version also called MailerSend US-only.
- 2026-10-21: an earlier version said MailerSend publishes no EU-region option and that all traffic terminates on US infrastructure. MailerSend’s privacy policy says its data storage centres are in the EU.