Thirteen SMTP and email providers publish a $0 tier, but the shapes vary. One is a trial with a hard end date. Two stamp branding into every message. Two are mailboxes rather than transactional relays. The rest carry either a daily cap, a monthly cap, or both. Filter this list on the caps that matter for your traffic, and every row that survives is a provider that fits.
Every provider here is one nanoPost has reviewed against its pricing page. The data behind the filter comes from the same nanoPost dataset that powers the review pages, so a filter combination on this page produces the same shortlist a manual read of the reviews would.
Showing 16 of 16 providers with a free tier.
| Provider | Type | Daily cap | Monthly cap | Notes | CTA |
|---|---|---|---|---|---|
| Elastic Email | Trial | no cap | no cap | Free plan with no stated expiry: 3,000 emails/month with a 100/day cap; SMTP relay and Email API access, plus 1,000 contacts for the marketing side | Read review → |
| Gmail | Trial | no cap | no cap | Free plan with no stated expiry: 500 emails/day for consumer @gmail.com accounts. OAuth2 or App Password auth. DKIM is signed by Google on gmail.com (no custom-domain DKIM without Workspace). | Read review → |
| Maileroo | Trial | no cap | no cap | 3,000 outbound and 1,000 inbound emails/month, 2 verified domains, no credit card, no time limit. Full feature set (SMTP, API, webhooks, inbound routing) – no gating vs paid tiers. | Read review → |
| MailerSend | Trial | no cap | no cap | 500 emails/month, MailerSend footer on messages, 1-day log retention, 1 domain, 1 user seat, 100 API requests/day. Needs an approved account and a card on file (not charged). No time limit. Overage $1.50/1K. No-card Sandbox mode sends 100 emails/month, to 2 recipients until approval. | Read review → |
| Mailgun | Trial | no cap | no cap | Free plan: 100 emails/day; pricing lists API and SMTP, one custom sending domain and webhooks, with no expiry stated. Mailgun's docs conflict on whether a no-card account can use a non-sandbox domain; see New accounts. | Read review → |
| Mailjet | Trial | no cap | no cap | Free plan with no stated expiry: 6,000 emails/month with a 200/day cap. Mailjet logo appears on free-tier emails; the $19/month 15,000-a-month plan removes it. | Read review → |
| MailPoet | Trial | no cap | no cap | Starter plan, no stated expiry: up to 500 subscribers and 5,000 emails/month via the MailPoet Sending Service. MailPoet branding on emails; free MailPoet Sending Service included once MailPoet approves the plan. | Read review → |
| Netcore Email API (formerly Pepipost) | Trial | no cap | no cap | Forever Free Plan, no stated expiry: first month 30,000 email credits with a 1,000/day cap, then 100 emails/day thereafter. | Read review → |
| Postmark | Trial | no cap | no cap | Free Developer plan: 100 emails/month; Postmark says it never expires. Intended for testing, deliverability evaluation, and low-volume side projects; no overages. | Read review → |
| Resend | Trial | no cap | no cap | Free plan: 3,000 emails/month, 100/day, no stated expiry in the pricing information; terms let Resend change or end the plan without notice; 3 domains | Read review → |
| SendGrid | Trial | no cap | no cap | Trial only: 100 emails/day for 60 days, no credit card, then the trial expires. Not a permanent free tier. New accounts may be vetted first. | Read review → |
| Brevo (Sendinblue) | Trial | no cap | no cap | Free plan with no stated expiry: 300 emails/day once Brevo approves the account, full SMTP and API access, no credit card. Free-plan emails carry the Sent with Brevo sticker. Shared cap between marketing campaigns and transactional sends on the account. | Read review → |
| SendPulse | Trial | no cap | no cap | 12,000 emails/month, capped at 400 per day and 50 per hour. 2 sender domains, 3 sender addresses. SendPulse says the SMTP Test plan moves to the free plan after you authenticate a domain and add a sender address on it. Its setup guide does not state whether moderation applies on this path. The previous setup uses an application form followed by profile moderation, usually up to 24 hours. No credit card, no time limit. | Read review → |
| SMTP2GO | Trial | no cap | no cap | Free plan with no stated expiry: 1,000 emails/month with a 200/day cap, no credit card, 5-day reporting, ticket-only support after the first 14 days | Read review → |
| Bird (formerly MessageBird, formerly SparkPost) | Trial | no cap | no cap | Free plan: 1,000 emails/month with a 50/day cap; sending stops at the limit | Read review → |
| Zoho Mail | Trial | no cap | no cap | Mailbox plan, not a relay: up to 5 users, 5GB/user, one domain, select data centres only. IMAP/POP/ActiveSync not included; Zoho documents SMTP settings for free organisations | Read review → |
Free-tier data is verified against each provider’s live pricing page and dashboard, then loaded into this tool from the same nanoPost dataset the reviews use.
“Permanent” tiers have no documented expiry; “Trial” tiers end after a fixed window; “Sandbox” tiers permit only testing, not production use.
Where a provider has an affiliate link, the CTA carries UTM tags (utm_source=nanopost, utm_medium=tool, utm_campaign=free-tier-comparator); otherwise it links to the nanoPost review.
How the filters work
- Daily cap. A minimum in emails-per-day. Providers with no daily cap always qualify, so the filter drops only the ones whose published daily ceiling falls short. Set this if the traffic clusters: a flash sale, a bulk subscriber notification, a form spam wave.
- Monthly cap. A minimum in emails-per-month. Same rule: providers with no monthly cap always qualify. Set this to the site’s realistic month-in-month-out volume, not the peak day scaled up.
- Permanent free tier only. Drops trial tiers (SendGrid’s 60-day window is the canonical example).
- No provider branding in messages. Drops providers that stamp their logo or a “sent via” footer into every message. Mailjet’s free tier and MailPoet’s free Sending Service both do this; the paid tiers remove it.
- SMTP relay / HTTP API available. Two independent filters. Every provider except MailPoet exposes both on the free tier; MailPoet’s free tier is only reachable from inside the MailPoet plugin, so both checkboxes drop it.
Where the data comes from
- Source of truth. A free-tier snapshot for each provider, maintained by nanoPost: the daily and monthly caps, whether the tier is permanent or a trial, whether messages carry provider branding, and whether SMTP and HTTP API are on the free tier. Every snapshot is dated, and a monthly pass re-checks the numbers against the provider’s pricing page and dashboard.
- What is not in the filter. Provider-specific catches that don’t fit a checkbox: Brevo’s shared marketing-and-transactional daily cap, Gmail’s consumer-only limitation, Zoho Mail’s dynamic hourly ceilings. The notes column carries these, and the underlying review page carries the full context.
When this tool is not the right question
If the site is genuinely going to stay under a thousand transactional messages a month, the answer is SMTP2GO and this tool isn’t earning its keep. SMTP2GO is the default recommendation because 1,000/month with a 200/day cap covers most WordPress sites without ceremony. The tool comes into its own when the traffic pattern is unusual (heavy daily bursts, marketing plus transactional on one account, need for a specific integration path) and the default doesn’t obviously fit.
When you’re ready to look wider than the free tiers, the Free SMTP servers for WordPress roundup covers each provider’s fit in prose, and the SMTP cost calculator ranks providers by cost for volumes above the free-tier ceilings. If the question is really “which SMTP plugin should I use on WordPress?” rather than “which provider?”, the best WordPress SMTP plugins roundup starts there instead.
Corrections
- 2026-11-11: an earlier version said SMTP2GO’s free plan adds no branding to messages, which SMTP2GO does not state.
- 2026-11-09: an earlier version counted two trials and one testing sandbox that prohibits production use. The list has one trial. Postmark’s free plan, the one listed as a sandbox, never expires according to Postmark, which lists low-volume side projects among its uses.