Why host mail is often not enough
Course sites send mail that students must receive: account creation, password resets, enrollment confirmations, payment receipts and failed-payment notices. The WP Mail SMTP plugin listing explains the root problem: WordPress uses PHP's mail function by default, many hosts are not configured to send it reliably, and mail without proper authentication can land in spam or vanish.
Host limits compound this. Kinsta says it does not provide email as part of its hosting plans, and it limits transactional email per plan, shared across all sites on the plan: 150 per day on entry plans such as Single 35k and Single 65k, 1,000 per day on mid plans, and 3,000 per day on the largest. It also states that its transactional email service does not currently support DMARC alignment and recommends a third-party SMTP service if you need DMARC compliance. SiteGround sends up to 400 emails per hour per site on StartUp and GrowBig and 800 on GoGeek and Cloud, with each recipient counted separately.
On DigitalOcean, SMTP ports 25, 465 and 587 are blocked on all Droplets and DigitalOcean recommends a dedicated deliverability platform. App Platform containers cannot open SMTP ports either. On either product, configure a mailer that sends over the provider's HTTPS API rather than SMTP.
Published free tiers and entry plans on 29 October 2026
| Service | Free allowance | Entry paid plan | Notes |
|---|---|---|---|
| Mailgun | 100 emails per day, 1 custom sending domain, 1 day of logs | Basic from $15 per month for 10,000 emails; extra from $1.80 per 1,000 | One day of logs is short for diagnosing a student's missing email |
| Postmark | 100 emails per month, no overages | Basic $15 per month for 10,000 emails; extra $1.80 per 1,000 | Separates transactional and broadcast mail into message streams |
| SMTP2GO | 1,000 emails per month | Starter $10 per month or $100 per year for 10,000 emails; extra $1 per 1,000 | Free plan phone and chat support limited to 14 days |
| Amazon SES | New AWS customers get up to $200 in Free Tier credits usable on SES; AWS says the free plan is available for 6 months after account creation | A la carte $0.10 per 1,000 outbound emails; attachments $0.12 per GB | Cheapest at volume but more setup; plan tiers with higher per-email rates also exist |
Worked example: launch day volume
Assume a cohort launch brings 300 new enrollments in one day and each enrollment triggers three emails: account welcome, payment receipt and a course access notice. That is 900 emails, before password resets and admin notifications.
Against published limits: Kinsta's 150-per-day entry plans would cap out after 50 enrollments; Mailgun's free 100 per day would be exhausted almost immediately; Postmark's free 100 per month, with no overages allowed, is for testing only; SMTP2GO's 1,000 per month free tier would be nearly used up in a day. Any of the entry paid plans at 10,000 emails per month would cover the launch and a normal month after it. On SES the same 900 emails would cost about 9 cents at the a la carte rate.
If you also send newsletters, do not push them through the same transactional account without separation. Postmark, for example, says transactional and marketing mail never mix and uses separate message streams.
Authentication rules your mail must meet
Google's sender guidelines require every sender to Gmail personal accounts to set up SPF or DKIM, have valid forward and reverse DNS for sending IPs, use TLS and keep spam rates reported in Postmaster Tools below 0.3%. Senders of more than 5,000 messages per day to Gmail must set up SPF and DKIM and a DMARC record (policy can be none), align the From domain with SPF or DKIM, and support one-click unsubscribe on marketing and subscribed messages.
A course site rarely hits 5,000 per day, but the DMARC and alignment steps cost nothing and protect launch days. This is also why Kinsta's note about DMARC alignment matters: if your domain publishes a strict DMARC policy, mail that is not aligned can be rejected.
Choosing between them
- Low volume, want simplicity: an entry paid plan from Postmark, Mailgun or SMTP2GO; the free tiers are for testing.
- Price-sensitive at volume and comfortable with AWS: Amazon SES, accepting more setup work for domain verification and sending limits.
- Need to investigate missing-email complaints: favour longer log retention; Mailgun's free tier keeps one day.
- Plugin compatibility: the free WP Mail SMTP plugin lists Mailgun, Postmark, SMTP2GO, SendGrid, Brevo and others as mailers; Amazon SES is listed as Pro-only, and email logging is a Pro feature.
Setup and acceptance checks
- Verify the sending domain at the provider and publish its SPF and DKIM records; add a DMARC record.
- Set the From address to your own domain, not a free mailbox address.
- Send test messages for each trigger: registration, password reset, purchase receipt, failed payment and course enrollment.
- Check message headers at a Gmail and an Outlook mailbox and confirm SPF, DKIM and DMARC pass.
- Check the provider's logs show each test message and that bounces are visible.
- After any host migration, repeat the tests: API keys, DNS records and outbound port rules can change with the host.
Questions before you decide
Can I send WordPress email from a DigitalOcean Droplet over SMTP?
DigitalOcean's Droplet limits page says SMTP ports 25, 465 and 587 are blocked on all Droplets and recommends a dedicated deliverability platform. Use a provider's HTTPS API mailer.
Does Kinsta include email?
Kinsta says it does not provide email as part of its hosting plans. It allows capped transactional email per plan and recommends a third-party SMTP service if you need DMARC compliance.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- Kinsta: Transactional email Accessed 29 Oct 2026
- SiteGround KB: Acceptable use of SiteGround's email service Accessed 29 Oct 2026
- DigitalOcean: Droplet limits Accessed 29 Oct 2026
- DigitalOcean: App Platform limits Accessed 29 Oct 2026
- Mailgun: Pricing Accessed 29 Oct 2026
- Postmark: Pricing Accessed 29 Oct 2026
- SMTP2GO: Pricing Accessed 29 Oct 2026
- Amazon SES: Pricing Accessed 29 Oct 2026
- Google Workspace Admin Help: Email sender guidelines Accessed 29 Oct 2026
- WordPress.org: WP Mail SMTP plugin Accessed 29 Oct 2026
Sources link directly to providers. Product buttons may use separately labeled affiliate links. Read our disclosure.