AI Email Tools for Small Agencies

Overview

AI email marketing tools for agencies are not one category of feature. A platform may generate a subject line, write a paragraph, design an entire campaign, choose a send time, or analyse a segment. Those jobs are often split between tiers, so an agency that sees an AI badge on a pricing page still needs to ask what the badge actually does.

This comparison reads the official pricing and help pages for Kit, MailerLite and Brevo on 3 November 2026. It focuses on a small agency managing its own list or several client campaigns, not on an enterprise marketing department. The practical questions are simple: what can the AI create, what can it optimise, what is included in Free, and what list or send limit forces the next upgrade?

The answer is unusually uneven. Kit gives Free users a real but narrow AI subject line tool. MailerLite has the clearest native copy assistant, but the writing tool begins on Comfort. Brevo has a wide AI layer called Aura, yet its pricing page separates the dedicated content generator from AI send-time optimisation. That makes Brevo attractive for a team that wants campaign automation, but it requires more careful interpretation of the word AI.

The three platforms at a glance

The table below keeps the pricing units separate. Kit counts active subscribers and publishes a broadcast allowance but no numeric monthly send cap on the pages read. MailerLite combines active-subscriber pricing with monthly email allowances. Brevo lets the buyer select a monthly email volume, and that choice sets the contact tier on the paid plans.

What the free plan actually includes

Kit Free costs 0.00 per month, read 3 November 2026. It supports up to 10,000 subscribers and unlimited email broadcasts. The official pricing page does not publish a numeric monthly send cap. The AI subject line generator is available five times. Each use creates a set of five subject line suggestions, and refreshing that set consumes another use. Free also includes unlimited landing pages and forms, tagging, segmentation and the ability to sell digital products or subscriptions. The trade-off for an agency is team access: the pricing comparison lists one user on Free.

MailerLite Free costs 0.00 per month, read 3 November 2026. It supports 250 subscribers and 2,500 monthly emails, with two user seats. The plan includes campaign sending, three visual automations, one website, one landing page, three signup forms and pop-ups, A/B testing, and the MCP server. Its AI subject line generator is available with a limited amount of credits. The AI writing assistant is not included on Free. The premium feature trial lasts 14 days, with no credit card required, and the account remains free after the trial if the agency does not upgrade.

Brevo Free costs 0.00 per month forever, read 3 November 2026. It stores up to 100,000 contacts, but sends only 300 emails per day. Unused sends do not roll over. One marketing seat is included, and up to 2,000 unique contacts can enter active automations. The Free plan includes basic reporting, email campaigns, a drag-and-drop editor and Aura, Brevo's AI-powered assistant. It always carries the Brevo sticker, and it does not include email A/B testing, advanced reporting, landing pages or popups.

The Free comparison is therefore about different constraints. Kit's hard number is the five-use AI allowance and one user. MailerLite's hard numbers are 250 subscribers and 2,500 monthly emails. Brevo's contact storage looks large, but 300 daily sends means a full broadcast to more than 300 recipients cannot go out in one day on Free. An agency should not choose Brevo Free for a client newsletter merely because the contact allowance says 100,000.

Kit: the subject line tool is free, the body copy is not a stated feature

Kit is the cleanest option for an agency that already writes its own emails and wants help at the subject line step. Its official help article says the AI subject line generator reads a Broadcast and produces five suggestions. It is available for Broadcasts, not Sequences. Free users can try it five times. Paid plans have unlimited access.

That is a more useful free feature than a vague “AI assistant” label. A strategist can draft a real client email, ask for alternatives, and keep the final decision with the account owner. It is enough to judge whether the suggestions fit the client's voice before committing to a paid account. It is not enough for an agency that wants to generate a complete campaign from a brief every day.

The free list allowance is strong. Kit Free is 0.00 per month for up to 10,000 subscribers, read 3 November 2026, and includes unlimited broadcasts. Kit's pricing page does not state a numeric monthly send allowance, so the honest comparison is not “unlimited sends.” It is “unlimited broadcasts, with no numeric monthly send cap published on the page read.” That distinction avoids turning a missing number into a promise.

Creator is displayed at 33.00 per month when billed yearly, or 390.00 billed yearly at the 1,000-subscriber view, read 3 November 2026. The plan has unlimited subscribers in the comparison table and includes visual automations, sequences, Kit MCP, integrations, support and the removal of Kit branding. Pro is displayed at 66.00 per month at the 1,000-subscriber view, read 3 November 2026, with unlimited subscribers. Pro adds engagement analytics, Subscriber Signals, unlimited users, deliverability reporting, collaborative editing and a newsletter referral system.

Kit's 14-day free trial is available for the paid plans, with no credit card required, read 3 November 2026. There is no need to use the trial to unlock the basic AI subject line test, because Free includes five uses. The trial is more useful for checking automations, team work and the paid analytics layer.

The boundary is content generation. Kit's AI product page describes email writing tools that generate and test subject lines, plus Kit MCP and an app ecosystem. The pricing and help pages fetched for this article do not verify a native AI email body generator tied to Free, Creator or Pro. An agency can connect external AI tools through Kit MCP on paid tiers, but that is different from saying Kit's editor includes native body-copy generation. This article does not make that unsupported claim.

Kit's best agency use is a light-touch editorial workflow: the strategist writes the offer and proof, Kit produces subject-line options, and the human keeps responsibility for the client voice. Choose Creator when automations and several team workflows matter. Choose Pro for analytics, collaboration and deeper audience signals, not because the subject line generator suddenly becomes available.

MailerLite: the clearest native AI copy tier

MailerLite makes the most explicit split between AI writing and AI subject lines. Its HeyLite documentation says the AI writing assistant is available on Comfort and Power. Comfort gets a limited amount of credits, while Power gets the most credits. The assistant works inside the drag-and-drop campaign editor, landing page editor and pop-up editor. It can generate titles, paragraphs and calls to action, and it can rewrite existing text.

The subject line generator is less restricted. MailerLite says it is available on all plans, including Free. Free has a limited amount of credits, while Comfort and Power have the most credits. The tool creates several suggestions from the campaign context, and the official help page warns that both prompts and responses consume credits. That means Free is suitable for a small agency learning the workflow, but not for an account that needs unlimited drafting across several clients.

Comfort starts at 12.00 per month, read 3 November 2026. The entry display states 5,000 monthly emails and three user seats. Comfort also adds 50 automations, ten websites, five digital products or bookings, paid newsletters, RSS campaigns, the subject line generator, the AI writing assistant and smart sending. Power starts at 25.00 per month, read 3 November 2026. It adds unlimited monthly emails, unlimited user seats, unlimited automations, unlimited sites, unlimited forms and 24/7 live chat and email support.

MailerLite prices paid accounts by active subscribers and usage tiers. The official pricing page explains that billing is based on active subscribers, and the product pages show the email volume for the entry display. They do not provide one universal subscriber cap for all Comfort or Power accounts in the pages read. A small agency should therefore treat 12.00 and 25.00 as starting prices, not as the final bill for a growing client list. The list tier selected at checkout is the number that matters.

Free costs 0.00 per month, read 3 November 2026, and allows 250 subscribers plus 2,500 monthly emails. That cap is easy to understand. A list of 200 people receiving four newsletters in a month uses 800 sends, leaving room for a welcome sequence. A list of 250 people receiving ten campaigns uses the whole 2,500 allowance. MailerLite's Free plan is therefore practical for a small pilot, but not for a busy agency sending the same campaign to several client audiences.

Smart sending is the other important gate. MailerLite describes it as an AI system that examines subscriber opens, clicks, signup date and time zone to send at an individually tailored time. It is on Comfort and Power, not Free. The feature has a different value from copy generation. It can improve the operating workflow after the copy is approved, but it needs enough historical activity to be useful. An agency should not pay for smart sending merely to solve a copy bottleneck.

Brevo: separate Aura, content generation and send-time AI

Brevo requires the most careful reading because its AI appears in several places. The Free plan includes Aura, which Brevo describes as an AI-powered assistant. The Aura help page says its Marketing agent can generate a full email campaign design, write subject lines, create or refine campaign content, translate templates, send at the best time, and segment audiences. The pricing page, however, names the “AI content generator” as a Starter feature and “AI send time optimization” as a Standard feature.

Those statements are not necessarily contradictory, but they do not provide a complete matrix for every Aura action on every tier. The reliable buying conclusion is narrower. Free definitely includes Aura. Starter definitely lists the dedicated AI content generator. Standard definitely lists AI send time optimization. The official pages fetched do not clearly say that every Marketing agent action exposed through Aura is unrestricted on Free. An agency should check the account's current feature prompt before promising a client a specific Free workflow.

Brevo Free is 0.00 per month forever, read 3 November 2026. It stores up to 100,000 contacts and permits 300 email sends per day. A campaign to 900 contacts can be sent only to 300 recipients on the scheduled day, with manual requeueing needed for the rest. That is the practical limit, even though the contact storage number is large. Free also caps active automation entry at 2,000 unique contacts and includes one marketing seat.

Starter begins at 9.00 per month, read 3 November 2026. The first official pricing tier is 5,000 monthly emails and 500 contacts. The next listed tiers are 10,000 emails with 1,500 contacts and 15,000 emails with 2,500 contacts. Starter lists the AI content generator, advanced segmentation, forms, basic reporting, MCP for ChatGPT and Claude, and no Brevo logo as a paid feature set. The price is attractive for a small list, but the contact limit moves with the selected send tier.

Standard begins at 18.00 per month, read 3 November 2026. The first tier also shows 5,000 monthly emails and 500 contacts, read 3 November 2026. Standard includes the Starter features plus unlimited multi-step marketing automation, A/B testing, advanced reporting, one landing page and AI send time optimization. It is the first Brevo tier in this comparison where the send-time feature is explicitly priced into the plan rather than left to a general assistant.

Brevo's official pages do not publish a paid-plan trial length for the Marketing plans read on 3 November 2026. Free is a permanent plan, not a trial. That missing trial length is itself useful information. Do not put a 14-day or 30-day Brevo trial into a client recommendation unless the vendor presents that term in the account or a current offer.

The cost of the send limit, not just the AI limit

The natural temptation is to compare 0.00, 9.00 and 12.00, then choose the lowest paid tier with an AI label. That misses the campaign arithmetic. A client list of 400 contacts cannot be handled in one day by Brevo Free's 300-send limit. A MailerLite Free account can hold only 250 subscribers, even though its 2,500 monthly send allowance looks generous. Kit Free can hold 10,000 subscribers, but the official page does not state a numeric monthly send cap.

Count each audience that will receive each campaign, then add welcome emails, resends, automated reminders and test messages. Brevo counts daily sends on Free and monthly email volume on paid tiers. MailerLite counts monthly emails and active subscribers. Kit presents subscriber tiers and broadcast access rather than a numeric monthly email allowance on the fetched page. The AI draft may be free, but delivery still consumes the platform allowance.

A practical choice for a small agency

Choose Kit Free when the agency wants a large free list, unlimited broadcasts as stated on the pricing page, and occasional subject line help. Choose Creator or Pro when automations, reporting, collaboration or subscriber insight justify paying. Do not choose Kit expecting a verified native body-copy generator or a published numeric monthly send quota. Choose MailerLite when AI writing inside the editor is the priority, and Brevo when contact-based pricing, transactional messaging or a named campaign content generator matters. Brevo Free is useful for testing Aura, but not for sending a full campaign to more than 300 recipients in one day.

For the broader agency comparison, the best email marketing platform for agencies covers client audiences, seats and platform fit. The MailerLite versus Kit comparison puts those two plans side by side. The Kit review explains that product's list and workflow model, while the MailerLite review goes deeper into its pricing tiers and feature boundaries.

Frequently asked questions