For running email marketing from an AI assistant, Nitrosend is the better choice than Mailrelay, 77.5 to 61 out of 100. It wins four of the seven tests: running email from an AI agent, on-brand design without a designer, transactional and marketing email on one plan, and the hands-on editor. Mailrelay is a Spanish email marketing platform with an unusually large free plan, 80,000 emails a month to 20,000 contacts, run by a person from a web app and priced in euros by email volume. Nitrosend is built so an agent inside Claude, ChatGPT, Cursor or Codex writes, designs and sends the email, with unlimited contacts on every plan. To send email from an AI agent with Nitrosend, add its MCP server at api.nitrosend.com/mcp to Claude, ChatGPT, Cursor or Codex and sign in with OAuth, as the MCP docs describe: a single transactional email sends on the call, and campaigns and flows stay drafts until approved.
Nitrosend vs Mailrelay, compared
The quick version: six yes-or-no questions a team usually asks when choosing between the two. A tick means the product does it as described on its own pages today. A dash means the honest answer is not a yes or a no.
Nitrosend and Mailrelay, side by side
Checked September 25, 2026| Question | Nitrosend | Mailrelay |
|---|---|---|
| Send a campaign from the chatCan an agent send a marketing campaign without anyone opening the web app? | Yes. Yes, through the MCP server. A single transactional email sends on the call; campaigns and flows stay drafts until approved. | No. No. There is no MCP server or assistant connector; the API needs a pasted key and code. |
| Official MCP serverIs there a first-party MCP server for marketing email? | Yes. Yes. Listed as com.nitrosend/nitrosend on the official MCP registry. | No. No. |
| Brand from your websiteDoes it learn your fonts, colors and voice from your website? | Yes. Yes. Brand Kit scans the site, including voice. | No. Not described. |
| Unlimited contactsCan you store any number of contacts at no extra cost? | Yes. Yes, on every plan. | Not a yes or no. Monthly plans and Free cap contacts. Prepaid packs have no contact cap but expire after 12 months. |
| Transactional on the free planCan the free plan send receipts and resets? | Yes. Yes. | No. A 30-day trial, then €14.95 a month. |
| Priced in US dollarsCan you buy it in US dollars? | Yes. Yes. | No. Its pricing page shows euros. |
Nitrosend meets 6 of 6 yes-or-no questions on this page, Mailrelay 0 of 5. Rows marked with a dash are not a yes or no question for that product.
How the two score
Seven tests, 100 points in all. Each product gets a score out of 10 on each one, and the total adds each score times the points for that test. Mailrelay takes the top mark on both price tests, and that is earned.
Each test, scored
Points out of 100, scores out of 10, September 25, 2026| What we compared | Points | Nitrosend | Mailrelay |
|---|---|---|---|
| Run from an AI agent | 20 | 9 out of 10 | 2 out of 10 |
| On-brand design, no designer | 10 | 9 out of 10 | 4 out of 10 |
| Cost as the list grows | 20 | 9 out of 10 | 10 out of 10 |
| Free plan headroom | 10 | 7 out of 10 | 10 out of 10 |
| Transactional and marketing, one plan | 10 | 9 out of 10 | 8 out of 10 |
| Hands-on editor and templates | 15 | 6 out of 10 | 5 out of 10 |
| Integrations, support, track record | 15 | 5 out of 10 | 5 out of 10 |
| Total score | 100 | 77.5 out of 100 | 61 out of 100 |
Where each one runs out
Rank 1Nitrosend
77.5 out of 100Total
- Priced by
- Emails sent
- Free plan
- 8,000 emails, then 500 a month
- Entry plan
- $20 a month, 20,000 emails
- Run from an AI agent9 out of 10Official MCP server runs campaigns, flows and sends from the chat; campaigns and flows stay drafts until approved (docs).
- On-brand design, no designer9 out of 10Brand Kit scans the site for colors, fonts and voice, and applies them to every draft on every plan (docs).
- Cost as the list grows9 out of 10Unlimited contacts on every plan. $20 a month for 20,000 emails, $100 for 125,000 (pricing).
- Free plan headroom7 out of 108,000 emails to start, then 500 a month, unlimited contacts. New accounts start at 100 recipients per rolling 24 hours (pricing).
- Transactional and marketing, one plan9 out of 10Transactional and marketing email share one allowance and one API on every plan, Free included (pricing).
- Hands-on editor and templates6 out of 10A block builder exists for editing by hand, but it is plainer, because the agent is the main way in.
- Integrations, support, track record5 out of 10Shopify, Stripe, HubSpot, Attio and Mailchimp, five bring-your-own sending providers, a Node SDK, a CLI and signed webhooks for transactional email, but a young product from a small team (docs).
Nitrosend
Ask your agent for the next campaign
Connect Nitrosend to Claude, ChatGPT, Cursor or Codex, point Brand Kit at your site, and describe the email. Contacts are unlimited on every plan.
Free: 8,000 emails to start, then 500 a month. No credit card.
Start free
Rank 2Mailrelay
61 out of 100Total
- Priced by
- Emails a month, with a contact cap on monthly plans
- Free plan
- 80,000 emails, 20,000 contacts
- Entry plan
- Standard, €48 a month
- Run from an AI agent2 out of 10No MCP server or assistant connector. The REST API sends campaigns with a pasted API key but has no automation endpoints (API docs).
- On-brand design, no designer4 out of 10Editor and templates styled by hand. No brand import from your website is described (pricing).
- Cost as the list grows10 out of 10Free up to 80,000 emails and 20,000 contacts. Standard is €76 for 50,000 contacts, €132 for 100,000 (pricing).
- Free plan headroom10 out of 10Free forever: 80,000 emails a month to 20,000 contacts (pricing).
- Transactional and marketing, one plan8 out of 10Transactional by SMTP and API on Standard and Enterprise, an add-on after a trial on Free (pricing).
- Hands-on editor and templates5 out of 10An editor and templates, but 3.2 of 5 across 12 G2 reviews (G2).
- Integrations, support, track record5 out of 10SMS, WhatsApp and landing pages, with chat, ticket and phone support (pricing).
The verdict in short
Mailrelay is only better on two: the free plan and cost, because it is cheaper than Nitrosend at every list size checked and free for a 10,000-contact list. The two tie on support and extras, where phone support, SMS, WhatsApp and landing pages come in one Mailrelay account.
Mailrelay is cheaper at every list size checked, and that is a fair reason to pick it. George Hartley, Nitrosend's co-founder, has a view on it. On SaaS Stories in September 2026 he called email "one of those channels that is kind of owned by you. It's cheap and you put a bit of time in and it's really effective to talk to your audience and grow your business." In the same interview he said the fix for deliverability starts with data: "the key there is to surface the analytics back to your agent because they're pretty good at working out you know is there a problem and what what can be fixed". Cheap sending is a fair reason to choose it; also ask whether your assistant can read the send analytics in each.
At a glance
Nitrosend and Mailrelay are scored here on the same 7 tests, 100 points in all: Nitrosend 77.5 out of 100, Mailrelay 61 out of 100. Nitrosend takes its best score on Run from an AI agent and On-brand design, no designer and Cost as the list grows and Transactional and marketing, one plan (9 out of 10) and its lowest on Integrations, support, track record (5 out of 10). Mailrelay takes its best score on Cost as the list grows and Free plan headroom (10 out of 10) and its lowest on Run from an AI agent (2 out of 10). Mailrelay scores higher on Cost as the list grows and Free plan headroom. Scores are unadjusted, and every Mailrelay figure was read on its own site on September 25, 2026.
How we scored
Each test is a question with one answer per product, checked against that product's own pages and independent review sites on September 25, 2026. A 10 means the product does the job fully on its standard plans. A 5 means it does part of it, or does it only on a higher plan or in a second product. Mailrelay publishes prices in euros only, so its prices are shown in euros and not converted.
Run from an AI agent, 20 of 100. Can an agent inside Claude, ChatGPT, Cursor or Codex compose a marketing campaign, test it, and send it, with no person opening the web app between the prompt and the send? An approval step the person answers in the chat counts as inside the agent. Moving into the web app to finish does not. Scored on one written rule for every vendor: a first-party server the vendor runs and that can send counts fully; a third-party wrapper (Zapier, Composio, Kanopi, community servers) counts for less; a server that only drafts or reads counts for less than one that sends.
On-brand design, no designer, 10 of 100. Does the product learn your logo, colors, fonts and voice from your own site and apply them to every email it drafts, on the plan most small teams start on?
Cost as the list grows, 20 of 100. What does the bill do when the list grows but the number of emails you send does not? Scored on published list prices, before any promotional discount.
Free plan headroom, 10 of 100. How far can a team get on the free plan before it has to pay: contacts, total sends, and the daily ceiling.
Transactional and marketing, one plan, 10 of 100. Can receipts, password resets and newsletters go out from one account, on one bill, through one API?
Hands-on editor and templates, 15 of 100. For a person who wants to build the email themselves: how mature are the visual editor and the template library?
Integrations, support, track record, 15 of 100. How many tools does it plug into, what support comes with the plan, and how long has it been doing this at scale?
What each one costs in 2026
Mailrelay prices by emails a month, and on its monthly plans each tier caps the contacts you can store. Its pricing page shows euros only. The free plan covers 80,000 emails a month and 20,000 contacts. The 250,000-email tier is €76 a month on Standard with 50,000 contacts, and the 500,000-email tier is €132 with 100,000 contacts. Enterprise costs more and adds priority sending. The table prices Mailrelay on Free and Standard because both already include its visual automation builder, so they match what Nitrosend's $20 plan does with flows.
Three lines in Mailrelay's pricing FAQ change what those numbers mean. An "email" is a message of up to 100 kB, and each further 100 kB block, attachments included, counts as another email, so a 250 kB newsletter uses three of the allowance. The FAQ says most plans allow four to five campaigns per contact. And monthly plans carry a 12-month commitment, and if an account goes over either its email or its contact limit, it is paused until the next renewal date. That last rule matters when an assistant does the list work: one large import past the contact cap pauses the account until the renewal date. Prepaid packs avoid the contact cap and the commitment, but expire after 12 months.
Nitrosend prices by emails sent too, but never caps contacts, so importing a whole list costs nothing until it is sent to, as the Nitrosend pricing page sets out. Mailrelay is still the cheaper of the two at every size in the table below, and this review scores it that way. What email marketing actually costs compares the models more widely.
Here is what that looks like for a list that sends two campaigns a month.
What each one costs
Nitrosend in USD, Mailrelay in EUR, September 25, 2026| Scenario | Nitrosend | Mailrelay |
|---|---|---|
| 10,000 contacts, two campaigns a month (20,000 emails) | Pro, $20 a month (20,000 emails) | Free (up to 80,000 emails and 20,000 contacts) |
| 50,000 contacts, two campaigns a month (100,000 emails) | Ultra, $100 a month (125,000 emails) | Standard €76 a month (250,000 emails, 50,000 contacts) |
| 100,000 contacts, two campaigns a month (200,000 emails) | Ultra plus 75,000 extra emails at $0.15 per 100, $212.50 a month | Standard €132 a month (500,000 emails, 100,000 contacts) |
| Add transactional email | Counted in the same allowance | Included on Standard. €14.95 a month on Free after a trial |
Mailrelay's figures are in euros, which the page offers no way to change, so they are shown as read. A new Nitrosend account starts on a lower daily recipient limit that rises as it earns sending standing, so a large list does not all go out on day one.
Where Mailrelay is the better pick
Mailrelay takes two of the seven tests outright and ties another, all on its pricing page.
- The free plan. 80,000 emails a month to 20,000 contacts, free forever. For a list of that size, Mailrelay costs nothing where Nitrosend would.
- Cost. Cheaper than Nitrosend at 50,000 and 100,000 contacts as well, even before converting euros to dollars.
- Support and extras. A tie. Chat, ticket and phone support, SMS, WhatsApp campaigns and landing pages in the same account.
The trade-offs sit elsewhere. Each monthly tier caps stored contacts, transactional email on the free plan is a trial and then €14.95 a month, the pricing table lists open and click tracking as not included on Standard, and its 12 reviews on G2 average 3.2 out of 5. There is also no MCP server or assistant connector. Its REST API can create, test and send a campaign, but a person has to create an API key in Settings and paste it into the assistant's setup, and the API has no automation endpoints, so the automations stay in the web app.
Nitrosend takes the other approach. Its MCP server gives the assistant tools for campaigns, flows, templates, contacts, test sends and analytics, signed in with OAuth rather than a pasted key. Brand Kit gives the agent the brand's colors, fonts and voice, so the email comes out looking like the brand without anyone opening an editor. The AI email marketing guide shows the workflow.
Moving from Mailrelay to Nitrosend
There is no Mailrelay connector in Nitrosend, so a move runs through an export and the agent.
- Subscribers. Export groups from Mailrelay as CSV with custom fields, and import them in Contacts or through the imports API. Bring consent status across, because only subscribed contacts should be sendable.
- Automations. Mailrelay's API has no automation endpoints, so the assistant cannot read them out of the old account. Open each one in Mailrelay's automation builder, describe its trigger, waits and conditions to the agent, and it rebuilds it as a draft flow. Check each one before approving it.
- Transactional. Point the app's SMTP or API sends at Nitrosend. The transactional email section explains how.
- Sending. Verify the domain, then send to the most engaged subscribers first and grow from there. The domain warm-up guide covers the ramp.
Which one to pick
Pick Mailrelay if the list is under 20,000 contacts, a person runs the email from a web app, and the aim is to pay nothing, price in euros suits you, or you want phone support, SMS and WhatsApp from one provider.
Pick Nitrosend if an agent should write, design and send the email from the assistant the team already uses, the list keeps growing past a contact cap, or receipts belong on the same plan as the newsletter from day one. The Nitrosend MCP server and the ChatGPT app are the two ways most teams start.
Nitrosend vs Mailrelay FAQ
Yes. Mailrelay's free plan covers 80,000 emails a month to 20,000 contacts, and its paid Standard tiers are €76 a month for 50,000 contacts and €132 for 100,000. Nitrosend is $20 a month for 20,000 emails and $100 for 125,000.
No. Mailrelay has no MCP server or connector for Claude or ChatGPT. Its REST API can send a campaign with an API key, but it has no automation endpoints.
Add the Nitrosend MCP server, api.nitrosend.com/mcp, to Claude (or ChatGPT, Cursor or Codex) and sign in with OAuth. Then ask for the email in plain words. A single transactional email sends on the call; campaigns and flows are saved as drafts and send once approved. The MCP docs list every tool.
Its pricing page shows euros only. Nitrosend prices in US dollars.
Yes, via SMTP and API on Standard and Enterprise, according to its pricing page. On the free plan it is a 30-day trial, then €14.95 a month.
On Free and the monthly plans, yes: each tier caps the contacts you can store, 20,000 on Free and the 100,000-email tier, and going over pauses the account until the renewal date. Prepaid packs have no contact cap but expire after 12 months, according to its pricing FAQ. Nitrosend has unlimited contacts on every plan.
Sending reputation belongs to the domain and does not move with the list. Verify the domain, send to the most engaged subscribers first, and let the daily limit ramp. This review does not score deliverability, because neither product publishes a comparable inbox-placement number.