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Bulletproof SMTP server

Bulletproof SMTP server: bulk sending that keeps working

When one server has a bad day, your campaign should not. BulkResponse rotates mail across managed SMTP servers, shows failures instead of hiding them, and sorts bounces correctly. Managed servers from $20/month, 5,000 emails a day each.

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Rotation across serversUp or Down per connectionSending policies apply

4.4Trustpilot (18)4.7G2 (3)4.3Capterra (3)

SMTP rotation on one campaignEach server keeps its own From and speed

Example

Server 1

5,000/day

Server 2

5,000/day

Server 3

Paused, error shown

Down

Server 4

5,000/day

The short answerLast reviewed October 2026

A bulletproof SMTP server is one that keeps delivering when a single path fails. At BulkResponse that means managed SMTP servers you can rotate on one campaign, failures that pause a campaign with a visible error, bounce handling that tells a temporary delay from a dead address, and suppression that stops repeat mail. Managed servers are $20 a month and send up to 5,000 emails a day each. Sending policies apply.

Two meanings

What does "bulletproof SMTP" mean?

The term gets used two ways online. Here is which one we sell, stated plainly.

What we sell: resilient sending

Several SMTP servers rotated on one campaign
Up or Down status on every connection
Auto-pause with a visible error past the failure threshold
Hard and soft bounces classified separately

What we do not sell: abuse-tolerant hosting

Ignoring abuse reports or complaints
Offshore hosting that hides who is sending
Sending without unsubscribe or suppression
Unlimited sending with no capacity limit

Resilience

What makes an SMTP setup resilient

Rotation across servers

Pick several SMTP servers on one campaign. Sends rotate, and each server keeps its own From email.

Speed limits per connection

Set per-minute, per-hour and per-day limits on every server. That is the throttle.

Auto-pause on failure

If a connection keeps failing past the threshold, the campaign pauses with an error you can read.

Parallel sending

Selected servers send at the same time, so one slow path does not hold up the rest.

Up to 10 bounce mailboxes

Tie a bounce mailbox to each SMTP connection and test it before saving.

Suppression that sticks

Bounced, unsubscribed and suppressed contacts are skipped on every later send.

Bounce handling

Hard bounces stop. Soft bounces are counted.

Bad bounce handling quietly ruins a sender. BulkResponse marks hard bounces on the subscriber, classifies soft bounces and delay notices separately, and records complaints. Suppressed and globally suppressed addresses never get the next campaign.

Hard bounce, soft bounce, complaint and unsubscribe are four separate statuses
Suppress typed emails, whole domains or an uploaded file
Export soft bounces, hard bounces and complaints from campaign stats

Sent

Message leaves

Bounce back

Read from bounce mailbox

Classified

Hard, soft or delay

Suppressed

Skipped next time

Domain setup

Authenticate your domain without guessing

DNS is where most new senders get stuck. We keep it to one SPF record and help you publish DKIM.

Add and verify your sending domainAdd it in account settings and click the link we email you.
Publish one SPF recordCopy the TXT record into your DNS. The domain list shows SPF status.
We help you publish DKIMAdding a domain notifies our support team, and we work through DKIM with you.
Track on your own hostnameOptional: opens, clicks and unsubscribes on your domain, over HTTPS.

TXT record for yourdomain.com

v=spf1 include:spf.bulkresponse.com -all

Need help? Open a ticket at help.bulkresponse.com or call +1 (628) 262 3981.

Compare

Shared relay vs managed server vs dedicated

Three ways to buy SMTP capacity from BulkResponse.

	SMTP Relay	Managed SMTP server	Dedicated (quote)
Best for	Your own software	Adding daily capacity to the Web App	High volume on assigned capacity
Price	From $29/month	$20/month per server	Custom quote
Capacity	Monthly credits, hourly ceiling	5,000 emails a day per server	Quoted to your daily number
Rotate on one campaign	Not applicable	Up to 20 servers	Yes
How you buy	Signup	Inside your Web App account	Talk to sales

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FAQ

Bulletproof SMTP server FAQ

What is a bulletproof SMTP server?

Is bulletproof SMTP legal?

Yes, in the sense we sell it. Here bulletproof means resilient: more than one path, visible failures and clean bounce handling. Sending policies apply to every account, and abuse reports are acted on.

What is the difference between bulletproof SMTP and bulletproof hosting?

Bulletproof hosting usually describes hosts that ignore abuse complaints. We do not sell that. BulkResponse sells resilient SMTP sending: rotation, monitoring of each connection, bounce classification and suppression.

Do you ignore abuse reports?

No. Sending policies apply to every account, and abuse reports are handled under those policies.

Does bulletproof SMTP mean unlimited sending?

No. A managed server sends up to 5,000 emails a day. You add capacity by adding servers, up to 20 (100,000 a day), or by asking for a dedicated quote.

Can I buy a dedicated IP?

Dedicated servers and dedicated IPs are sold on a custom quote based on your daily volume. There is no self-serve IP picker.

How can I tell if an SMTP connection is down?

Each connection shows Up or Down in your account. A connection that keeps failing past the threshold can pause the campaign with an error you can see.

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