Top 10 Email Marketing Tools
Email still returns roughly $36 to $42 for every $1 spent, which is why picking the right tool matters more than picking the right subject line. This guide compares the ten platforms most teams actually shortlist in 2025, with honest notes on who they fit and where they fall apart.
What It Actually Is
An email marketing tool is software that stores your contact list, sends broadcast campaigns, runs automated flows (welcome, abandoned cart, re-engagement), and reports on opens, clicks, and revenue. A small Shopify store using Klaviyo to send a 3-email welcome series the moment someone signs up is a typical example: the tool handles the list, the templates, the trigger, the send, and the revenue attribution.
Why It Matters (with data)
- Average email ROI sits at $36 to $42 per $1 spent, and 18% of companies report ROI above 7,000% according to Marketful's 2025 roundup.
- Klaviyo's analysis of 183,000 brands found the average campaign open rate is 31% and US e-commerce brands on Klaviyo see up to $72 per $1 spent, per Klaviyo's industry benchmarks.
- Automated flows generate nearly 41% of total email revenue from just 5.3% of sends, which is why tool choice (and automation depth) drives most of the result.
- Klaviyo crossed $1B in revenue in 2024 with 167,000 customers and 34% YoY growth, reflecting how concentrated e-commerce has become on a single platform.
How It Works / The Playbook
The ten tools worth shortlisting in 2025:
- Klaviyo, The default for Shopify and BigCommerce stores. Deepest e-commerce data model, predictive CLV, SMS in the same platform. Paid plans start around $20/month for 500 contacts. Gets expensive fast above 50k contacts.
- Mailchimp, The most recognized brand. Great editor, weak automation on cheaper tiers. Paid plans start at $26.50/month for 1,000 contacts. Pricing scales steeply; automation is paywalled.
- ActiveCampaign, Best-in-class automation builder, 1,000+ integrations, strong for B2B and service businesses. Steeper learning curve than Mailchimp or Brevo.
- Brevo (formerly Sendinblue), Cheapest serious option: $9/month for 5,000 emails. Free plan allows up to 100,000 contacts. Includes SMS and a basic CRM. Won EmailToolTester's "Best Email Marketing Tool" pick for 2026.
- MailerLite, Clean editor, generous free plan (1,000 contacts, 12,000 emails/month), fair pricing. The "I just want it to work" pick.
- HubSpot, Email inside a full CRM. Strong for sales-led B2B teams that need lifecycle data in one place. Expensive once you outgrow the Starter tier.
- ConvertKit / Kit, Creator-focused. Tagging and sequences over campaigns. Best for newsletters, courses, and solo operators.
- Beehiiv, Newsletter-native, built-in ad network and referral program. The Substack alternative for serious publishers.
- Customer.io, Event-triggered messaging for product teams. SQL audiences, transactional and marketing in one place. Developer-heavy setup.
- Omnisend, Klaviyo's cheaper e-commerce alternative. Strong SMS and pre-built Shopify flows; smaller integration catalog.
How to actually choose:
- E-commerce store on Shopify with under $1M revenue: start on Omnisend or Mailchimp, graduate to Klaviyo around $500k.
- B2B SaaS with a sales team: ActiveCampaign or HubSpot.
- Creator, newsletter, or course: Kit or Beehiiv.
- Tight budget, mixed use case: Brevo or MailerLite.
- Product-led with engineers in the loop: Customer.io.
Living Proof, a Unilever haircare brand, moved to Klaviyo and reported a 30% lift in email revenue and a 4x increase in flow revenue within the first year, according to Klaviyo's customer story. On the other end, indie newsletter Morning Brew scaled past 4 million subscribers on a custom stack but routes paid acquisition flows through Beehiiv-style mechanics, illustrating that the "right" tool depends entirely on business model.
Common Mistakes
- Picking Mailchimp by default and discovering automation is paywalled at 10,000 contacts when migration costs are already high.
- Using Klaviyo for a B2B SaaS, you will pay an e-commerce premium for features your funnel will never use.
- Ignoring deliverability when comparing prices. A $9 plan that lands in spam costs more than a $50 plan that lands in the inbox.
- Treating contact count as the only pricing axis. Email volume, SMS, and API event limits often dominate the real bill.
- Building 14 flows before you have 1,000 subscribers. Tool choice rarely matters under 5,000 contacts; behavior does.
Key Takeaways
- For Shopify e-commerce above $500k revenue, Klaviyo is still the answer in 2025, the data integration gap is real.
- For everyone else, Brevo, MailerLite, and ActiveCampaign give you more for less than Mailchimp.
- Automated flows produce 41% of email revenue from 5% of sends. Pick the tool with the automation builder you will actually use.
