Everything you need for effective campaigns
Bulko brings together everything that usually needs to be manually pieced together: SMTP rotation, AI content variability, IMAP response collection with classification, trigger-based follow-ups, and analytics. No subscriptions.
Platform in review
Every feature is built for one goal — to increase the share of emails that land in the inbox and bring a reply.
SMTP rotation
Connect your own warmed-up SMTP or rent ours. Per-account limits, automatic rate control, disabling of failed accounts.
AI content variability
Every N emails — new text and subject via Gemini/OpenAI. Spintax {a|b}, merge-tags, A/B variants on the fly.
AI Reply Classification
All replies from IMAP land in a single inbox. AI labels them: positive / negative / question / bounce / auto-reply.
Trigger-based follow-ups
Automatic follow-up for positive replies. Stop-on-reply, manual confirmation, minimum AI confidence.
Analytics
Sent / Delivered / Opened / Clicked / Replied. Daily charts, breakdown by SMTP, CTR by subjects and content.
REST API
Launch campaigns, import addresses, and get statistics and replies via the Bearer API. Webhooks are under development.
Deliverability
SPF/DKIM/DMARC check, blacklist-checker, MX validation, bounce-code tracking. AI content filter before sending.
Lists and segments
CSV import, tag segmentation, automatic cleanup of invalid addresses via email validators.
Pay-as-you-go
No subscriptions. Credits do not expire. Pay by card or USDC via Stripe.
Ready-made sending infrastructure.
Campaign Platform does not require you to connect SMTP yourself: Bulko selects an available account from the managed pool and controls its limits. Custom SMTP is available only for selected special accounts.
Each account gets an individual rate limit (by default 20 emails/day for Gmail, up to 50K for SES). When the limit is reached, rotation automatically switches to the next valid SMTP.
If the SMTP provider returns an authentication error (535) or a temporary failure (421/450), the account is excluded from rotation and the campaign continues through the remaining ones. You get a notification about the problematic SMTP in the dashboard.
- Gmail / Workspace
- Outlook / Office 365
- Amazon SES
- SendGrid / Brevo / Mailgun
- Yandex / Mail.ru / Yahoo
- Zoho / FastMail / GMX
- Any standard SMTP
AI makes every email slightly different
The main reason cold campaigns end up in spam is that filters recognize the template. When 1,000 identical emails go out from a single template, providers see the pattern and send them all to spam at once.
Bulko obfuscates templates with four layers: spintax, merge tags, AI-rewrite of subject and body every N emails, and dynamic randomization of sentence order. As a result, no two emails are identical.
Use your OpenAI API key or Bulko's built-in AI credits (Gemini 2.5 Flash). You define the basic prompt — for example, 'selling a Python course for beginners, friendly tone'. The AI generates variations within this description.
- 1Spintax
{Hi|Hello}, instant - 2Merge tags
{{name}}from your list - 3AI rewrite: every N emails the subject and body are generated again
- 4Random subject: one button generates a new subject from context
AI sorts your incoming replies for you
When your outreach goes through 10 SMTP accounts, replies come to 10 different mailboxes. Bulko connects via IMAP to each SMTP and collects all replies into one shared inbox.
Then the AI classifier takes over. Each email is labeled into 5 categories: positive (interested), negative (refusal), question (needs details), bounce (address unavailable), auto-reply (vacation/out of office). A confidence score from 0 to 1 shows how confident the AI is.
In the «Replies» section, you only see what's important. By default, bounce messages are hidden, leaving positive and questions. Each reply immediately shows the campaign, sender, and AI analysis.
The second email is sent only to those who have shown interest
The first email is cold, without links or sales CTAs, with one goal: to get a response. If a positive response is received, Bulko automatically sends a follow-up with detailed information, a link to a demo, or a calendar after N hours.
Links and sales content are allowed in follow-ups: only those who have already shown interest receive them. This is not cold outreach, but a warm response to a request.
Parameters: delay from 1 hour to 1 week, minimum AI confidence (default 0.7), automatic or manual sending after your confirmation. If the recipient replies again before the follow-up, sending is canceled.
- 1Cold email goes out, without links or CTAs
- 2IMAP fetches the reply → AI classifier → positive
- 3After N hours, a follow-up with all the details is sent
- 4Stop-on-reply: a repeat reply stops further follow-ups
See the funnel, not just "sent"
Funnel
Sent → Delivered → Opened → Clicked → Replied. With absolute numbers and percentages at each step.
Trends
Daily charts for 14 days. See which day of the week gets the best open rate and when deliverability drops.
Breakdown
By SMTP — which account shows the best open rate. By subjects — which subjects get more opens and clicks.
06 · Integrations
REST API for your own systems.
Launch campaigns from your own script or a universal HTTP action in Zapier/n8n. Upload recipients, read statistics, replies, and balance via the Bearer API.
Outbound webhooks are not yet available in production and will be added after the REST API is stabilized.
Integrations documentation1POST /api/v1/campaigns/launch 2Authorization: Bearer YOUR_TOKEN 3Content-Type: application/json 4 5{ 6 "name": "Q2 Outreach", 7 "subject": "{Hi|Hello} {{name}}", 8 "body": "...", 9 "recipients": ["[email protected]", "[email protected]"], 10 "smtp_pool": "warmed-eu" 11}
Continuous infrastructure self-checks
Bulko provides built-in validators. Before launching a campaign, you can check if SPF/DKIM/DMARC are configured correctly, if the domain is on blacklists, and if MX servers are responding.
SPF Checker
Check the SPF record and allowed senders.
MX Checker
Check MX servers and priorities.
Blacklist Checker
Check the domain against 50+ public blacklists.
Email Validator
Email validity check via MX + SMTP.
AI Content Filter — built in
Every outgoing message — both from campaigns and via SMTP relay — is automatically scanned by a hybrid filter (heuristics + Gemini AI) for phishing, malware, brand impersonation, and scams. Suspicious content is blocked before sending and saved as a snapshot.
This keeps the IP pool's reputation high — so deliverability stays stable. Marketing, transactional, and cold outreach all go through without a hitch.
Ready to launch a campaign?
Import your list, write one email and let Bulko handle sending and follow‑ups.
- 500 free emails
- No card required
- Credits never expire