Tools we use to build and run newsletters
One canonical list of every external tool, host, API, and SaaS we actually use ourselves at onetwothreesend.com. The docs cross-link here so you can pick reliable defaults without us copy-pasting the same recommendations across pages. New tools get added as we adopt them.
Disclosure: some of the links below are affiliate links — if you sign up after clicking through, we earn a small commission, at no extra cost to you. We only list tools we use ourselves, and we do not pay for placement. If you’d rather skip the affiliate link, every tool below is also one quick search away.
Managed WordPress hosting
BigScoots
Managed WordPress hosting tuned for high-traffic publishers. Real-time monitoring, hands-on support that answers in minutes instead of hours, and the WP-Cron actually fires reliably on low-traffic sites (which matters for One Two Three Send’s scheduled-newsletter cron and One Two Three Post’s 5-minute Facebook publisher tick). If your current host has cron problems or your support tickets get bounced around, this is the upgrade.
Newsletter platforms
One Two Three Send keeps your subscriber list and sends from your own WordPress site. Some operators want a hosted alternative — these are the platforms we’ve used and would recommend.
MailerLite
Generous free tier (up to 1,000 subscribers), clean editor, automation that doesn’t feel like aerospace engineering. Best fit for newsletter operators who want hosted simplicity without the pricing ramp of bigger players. Pro plugin supports MailerLite directly as a provider — you can switch transports without leaving One Two Three Send.
Brevo (formerly Sendinblue)
European-based, GDPR-friendly newsletter and transactional service. Pricing scales by emails sent rather than subscriber count, which matters once your list gets large but you don’t email it often. Pro plugin supports Brevo as both a newsletter provider and an SMTP transport.
Beehiiv
Hosted newsletter platform built for monetisation — paid subscriptions, ad network, referral programmes, the works. Useful to know about even if you stay on One Two Three Send: the Pro plugin’s Beehiiv import endpoint pulls posts from a Beehiiv publication back into WordPress as drafts, so the two can run side-by-side if you’re consolidating.
Transactional email
Newsletter sends go through your chosen newsletter provider. The other email a WordPress site emits — password resets, admin notifications, contact-form receipts — needs its own delivery path. SMTP through your host’s mailer is fine for low-volume sites; serious deliverability needs a dedicated transactional service.
Postmark
Best-in-class transactional email reputation, simple API, and an admin dashboard that shows you exactly which messages went through, bounced, or got marked as spam. Used by every developer we know who cares about deliverability. Not a newsletter sender (Postmark explicitly refuses bulk lists) — pair it with one of the newsletter providers above.
AI / language models
Claude (Anthropic)
The LLM behind every AI feature in One Two Three Send and One Two Three Post: AI drafting, the full AI audit, AI Agents content generation, network listing moderation, and Post Pro’s text-question generator. Anthropic’s pay-as-you-go API is what you sign up for — no monthly commitment, you pay only for the tokens you use. A modest newsletter operation costs cents per month; a high-volume AI Agents publishing site costs single-digit dollars per month.
This page is maintained by hand. If a link is broken or a tool we mention has moved, drop a line via the contact form. If you’re a tool provider and want to be considered for inclusion: we only add tools we actually use, so the path is for us to use yours first.
Social publishing
Publer
Cross-network social publishing tool — Facebook, Instagram, LinkedIn, Threads, TikTok, X. We use Publer with the One Two Three Post 1.7.0+ plugin as the alternative “publishing transport” so operators who already pay for Publer don’t need to set up their own Facebook App and OAuth flow; the plugin sends posts to Publer’s API and Publer fans them out. Publer’s API is on the Business and Enterprise plans.
Sign up via our affiliate link: publer.com/onetwothreesend. Using this link supports the project at no extra cost to you — Publer pays us a small referral commission. FTC disclosure: this is a paid affiliate relationship.