Instantly vs Warmbox (2026): which should you pick?

Pick Instantly if

• Fits if you send from lots of mailboxes and don't want to pay per inbox or per seat
• Works for teams that want warm-up included rather than bought per mailbox

Look elsewhere if

• Skip it if you want LinkedIn steps in the same sequence, as Instantly is email only
• Tight if you stay on Growth, with 1,000 contacts in total, a read-only inbox and no webhooks
• Pricey if you need lead data too, since credits start at $9 a month for 150, and on Growth the CRM is only a 14-day trial
• Watch out: the contact limit is a running total, not monthly, and 25,000 more cost $87 a month
• Watch out: there's no free plan, and the trial stops at 250 contacts and 1,000 emails

Pick Warmbox if

• Fits if you send cold email from one or two new mailboxes and want a warm-up run in the background
• Works for agencies that connect many client inboxes and will ask for a custom plan

Look elsewhere if

• Skip it if you want a free try, because there is no trial or free plan
• Tight if you run more than 6 inboxes, as plans stop there and larger setups are custom
• Pricey if you add inboxes: $15 for 1 inbox becomes $69 for 3
• Watch out: the vendor says warm-up usually needs 15 to 30 days of uninterrupted running before results show
• Watch out: the pricing page doesn't say which billing period each of its two price sets applies to

Instantly

• There is no free plan; the 14-day trial stops at 250 uploaded contacts and 1,000 emails.
• The uploaded-contact limit is a total across all campaigns, not a monthly one. On Hypergrowth and up, 25,000 more contacts cost $87 a month.
• Lead data and the AI agents need an Instantly Credits plan, from $9 a month for 150 credits; on Growth the CRM is only a 14-day trial.
• Replying from Unibox, webhooks, the CRM and full A/Z testing need Hypergrowth, $107 a month billed monthly.

Warmbox

• The pricing page does not state which billing period each of its two price sets applies to; the default view shows $15 for Solo and the other toggle shows $19.
• Plans are sized by the number of inboxes (1, 3 or 6) and by emails a day, so larger setups need a custom plan.
• The vendor says warm-up usually takes 15 to 30 days of uninterrupted warming before results show.
• It warms mailboxes only; it does not send campaigns or find leads.

Instantly

Unlimited sending accounts and warmup

Every Outreach plan connects and warms up any number of email accounts from any provider; the plan limits emails sent and contacts uploaded instead.

Sequences and A/Z testing

Multi-step campaigns with sending schedules, a global block list and bounce detection. Growth gets basic A/Z testing; Hypergrowth and above test up to 26 variants.

Unibox

Replies from every connected account land in one inbox. It is preview-only on Growth; replying in the app and custom reply labels start at Hypergrowth.

SuperSearch lead database

Search more than 450 million B2B contacts and enrich them through several email providers, paid for with Instantly Credits, a separate subscription.

AI Sales Agent and AI Reply Agent

Agents that find and contact leads or draft answers to replies. Each lead or reply generated costs 5 credits from the credits plan.

Automations

A visual trigger-and-action builder routes and tags leads when they reply, visit your site or book a meeting, and is included on every Outreach plan.

Warmbox

Automated warm-up traffic

Sends and answers messages with a private inbox network, marks them as favorites and removes them from spam.

Warm-up profiles

Growth, flat or random volume patterns, a warm-up schedule and fully custom settings.

Realistic content

The page says replies are written to look human, using GPT-4 and a hybrid approach.

Checks and monitoring

A live email checker for DNS and blacklists, spam score monitoring and a reporting dashboard.

Many inbox types

Gmail and Google Workspace by OAuth, Microsoft 365, Yahoo, iCloud, AOL, Zoho, SendGrid, Mailgun, Amazon SES and any SMTP mailbox.

Agency use

Multi-account support for agencies and team members on every plan.

Instantly

• Growth$37.6

  per month for 5,000 emails, billed yearly ($47 monthly)

  1,000 uploaded contacts, unlimited email accounts and warmup, basic A/Z testing and a preview-only Unibox.

• Hypergrowth$85.58

  per month for 125,000 emails, billed yearly ($107 monthly)

  25,000 uploaded contacts, the built-in CRM, replying from Unibox, webhooks, A/Z tests of up to 26 variants and premium live support.

• Light Speed$286.3

  per month for 500,000 emails, billed yearly ($358 monthly)

  100,000 uploaded contacts, the CRM, and SISR, which rotates dedicated servers and IP addresses for sending.

• EnterpriseCustom

  More than 500,000 emails a month, a private deliverability network and a dedicated account manager.

Warmbox

• Solo$15

  per month for 1 inbox, billing basis unclear

  1 inbox warmed at up to 50 emails a day, 1 member and premium support. The page's other toggle lists $19.

• Start-up$69

  per month for 3 inboxes, billing basis unclear

  3 inboxes at up to 250 emails a day, 3 team members and premium support. The other toggle lists $79.

• Growth$139

  per month for 6 inboxes, billing basis unclear

  6 inboxes at up to 500 emails a day, 6 team members and enterprise support. The other toggle lists $159.

• TeamCustom

  Custom plans for larger sending volumes, quoted through the vendor's chat.

Instantly

• Annual discount

  About 20% off with yearly billing

  Billed yearly, Growth is $37.6 a month instead of $47, Hypergrowth $85.58 instead of $107 and Light Speed $286.3 instead of $358.

Warmbox

No public discounts listed.