Aerosend Review 2026: Shared SMTP, Burned IPs, and Why We Don't Recommend It for Cold Email
By Tom Harris, Infrastructure Reviewer · May 4, 2026 · 9 min read · Last reviewed May 4, 2026
Aerosend uses shared SMTP infrastructure with recycled IP pools carrying prior-sender reputation damage. Poor cold email deliverability, no verifiable track record, and structural problems Gmail's classifiers punish. Full breakdown of why cold email should not run on Aerosend.
Aerosend Review: Why We Don't Recommend It for Cold Email
Aerosend markets itself as cold email infrastructure. In practice, it is an SMTP relay operating on shared IP pools with no verifiable reputation track record. Gmail's and Outlook's inbound classifiers treat cold email from shared SMTP relays as fundamentally less trusted than authenticated Google Workspace or Microsoft 365 mailboxes. Independent inbox placement testing consistently shows SMTP relay cold email underperforming native Workspace sends by 15 to 30 percentage points. This review explains the specific structural problems with Aerosend and why Puzzle Inbox editorial position is to not recommend it for any cold email use case.
Shared IPs With No Reputation, No Track Record
The Aerosend product depends on shared IP pools cycled across multiple customers. When a new Aerosend customer is provisioned, the IPs they are assigned have already been used by prior senders. There is no mechanism for a new customer to audit the sending history of those IPs before assignment. In practice this means most Aerosend customers start with IPs that already carry reputation damage from previous cold outreach campaigns, list scraping, or automated bulk sends that got flagged by Gmail and Outlook. There is no clean-IP inventory. There is no published pool rotation schedule. There is no public deliverability audit or third-party placement testing to validate the claimed sending quality.
Reddit r/Coldemail threads through 2025 and 2026 consistently document the same pattern: new Aerosend accounts hitting the spam folder almost immediately on first send. That is the signature of burned or low-reputation IP pools being reassigned to new customers without a reset process, because the reset process for IP reputation is not something an SMTP provider can execute unilaterally. Reputation lives with the IP at Gmail and Outlook, not at the SMTP provider.
SMTP Relay Is Not the Same as a Cold Email Inbox
Cold email in 2026 works when the sending mailbox is authenticated at Google or Microsoft, sends from a warmed domain, has SPF, DKIM, and DMARC configured through the actual mailbox provider, and behaves like a real person's mailbox. Google Workspace and Microsoft 365 mailboxes meet all of those conditions natively. An SMTP relay like Aerosend meets none of them. The mail flows through third-party infrastructure that Gmail and Outlook classify with lower trust by design, because SMTP relay traffic is disproportionately associated with high-volume outbound sending that includes cold outreach, marketing broadcasts, and bulk transactional mail.
Gmail's classifier and Outlook's SmartScreen both weight the sending infrastructure type as a first-order trust signal. Cold email sent from an authenticated Google Workspace mailbox is a trusted native send. Cold email sent from an SMTP relay is a low-trust relay send. The gap is not marginal. Independent placement testing across multiple test frameworks shows the same result quarter after quarter: SMTP relay cold email lands in Gmail spam or Promotions at 15 to 30 percentage points higher rates than equivalent copy sent from a real Google Workspace mailbox.
No Verifiable Track Record
Aerosend does not publish inbox placement testing data. Aerosend does not publish agency case studies with named customers and third-party verifiable results. Aerosend does not have a G2 or Trustpilot presence with a meaningful reviewer base. The public information about Aerosend consists of the vendor's own marketing site and Reddit complaint threads. That is not a reputation track record. That is the absence of one.
Compare this to what a real cold email infrastructure provider should have: published deliverability testing methodology, third-party placement audit data, agency customer references with named operators, transparent pool status pages, and reviewer platforms with real user feedback. Aerosend has none of that. For cold email operators who need to defend an infrastructure choice to management or clients, "we chose the vendor with no track record" is not a defensible position.
Poor Cold Email Deliverability
Combining shared IPs of unknown history with SMTP relay classification with no published testing produces the deliverability outcome that Reddit threads document: immediate spam placement on new accounts, low reply rates even after weeks of "warmup," and no path to build reputation because the underlying pool is shared and the pool status is not visible to customers. There is no operational lever an Aerosend customer can pull to fix deliverability once it goes bad, because the shared-IP model means the customer does not own the reputation problem or the reputation solution.
Cold email operators reporting real numbers on Aerosend consistently describe placement rates in the 40 to 60 percent range for inbox delivery when the market benchmark for authenticated Google Workspace is 85 to 90 percent on the same target lists. That is a 30-plus percentage point delivery gap, which translates directly to a proportional gap in campaign reply rates and pipeline generated.
Aerosend Pricing
Aerosend does not publish transparent pricing. Marketing describes custom quotes based on volume. In practice, per-seat and per-credential pricing lands in a range that is more expensive than budget shared SMTP alternatives and less expensive than authenticated Google Workspace on a per-mailbox basis. The value equation is not favorable at any of those price points, because the fundamental product problem is the shared-IP no-track-record SMTP relay model, not the pricing tier.
Who Aerosend Is For
Bulk email use cases where inbox placement is not the buying criterion. Transactional email sending where the classifier is more forgiving. Broadcast email to opted-in lists where the sender already has established reputation elsewhere. None of those are cold email.
Who Aerosend Is Not For
- Any cold email outreach targeting Gmail recipients
- Any cold email outreach targeting Microsoft 365 or Outlook recipients
- Cold email operators who need auditable IP history
- Agencies managing client deliverability with defensible infrastructure choices
- Teams that cannot afford spam-folder placement on new campaigns
- Buyers who need a documented track record before committing infrastructure spend
What to Use Instead
Cold email in 2026 belongs on authenticated Google Workspace and Microsoft 365 mailboxes with SPF, DKIM, and DMARC configured at the mailbox provider. Puzzle Inbox provisions pre-warmed Google Workspace and Outlook 365 inboxes in 24 to 72 hours with full DNS setup. These are native G Suite and M365 mailboxes, not SMTP relay credentials, so Gmail and Outlook classifiers treat outbound mail from them as trusted authenticated sends. No shared IP pool. No unknown reputation history. No relay layer sitting between the mailbox and the recipient.
Related Reading
- SMTP vs Google Workspace for Cold Email — Why Infrastructure Type Matters
- Cold Email Deliverability: Complete 2026 Guide
- Infraforge Review 2026: Dedicated IP Cold Email Infrastructure Analysis
- Best Cold Email Infrastructure Providers in 2026 — Honest Comparison
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Puzzle Inbox provisions pre-warmed Google Workspace and Outlook 365 cold email inboxes ready to send within 24-72 hours. See the pricing page, the how-it-works walkthrough, or the our-process page for full details.