Sending.ac
Alternative & Review

The company was founded in 2024 by Yannic Schwock, Felix Seidel, Dharmendra Soni, and Thierry Maftoum.

Sending.ac positions itself as a provider of Azure-based cold email infrastructure; the platform highlights automated DNS setup and a focus on keeping emails out of spam folders. They also emphasize 100% isolation with a dedicated Azure outbound tenant per domain and avoid shared IPs, with automatic replacement every 14 days.

The company has no reviews on G2 or Trustpilot.

• "A lot of these were burned last month, mass microsoft tenant shut downs. Since then, a little bit sketchy."
• "you're correct, most microsoft infra providers got burned a few weeks ago. I did some digging on that and found the CEO of sending.ac talking about that very shutdown."

sending.ac : r/coldemail

🟢 Dedicated Azure outbound tenants. Sending.ac offers 100% isolation with a dedicated Azure outbound tenant per domain, enhancing deliverability and security.
🟢 No shared IPs with automatic rotation. The service ensures no shared IPs, with automatic replacement every 14 days, which helps maintain sender reputation.
🟢 Automated and fast mailbox setup. Mailbox setup is fully automated and quick, taking approximately 34 seconds per mailbox.

🔴 High minimum order. A minimum order of 450 mailboxes might be restrictive for smaller users or those just starting.
🔴 API access not publicly found. Information regarding API access for programmatic control is not readily available on their public res.
🔴 Self-healing features not explicitly mentioned. Beyond general isolation claims, specific self-healing or recovery features are not explicitly detailed.

Maildoso is a cold outreach infrastructure provider – we offer domains, SMTP mailboxes, and Google Workspace accounts. The company was founded in August 2023 in Granite Bay, California, by Nikita Bykadarov (Nikita Maildoso).

While other providers offer shared or dedicated IPs, we have developed IP rotation. This means your emails are sent from hundreds of different IPs (making it harder for spam filters to detect a sending pattern), and whenever any IP gets blacklisted, we automatically swap it out for a clean one.

We have also implemented self-healing mailbox technology, which both restores burned-out mailboxes and protects your active email accounts.

The result?
As of May 2026, the spam rate across our entire network of mailboxes is around 5%.

G2: 4.7/5 (181 reviews)

"Tried it mainly because of the good price, but ended up sticking with it since deliverability’s been pretty stable so far" – Thinking about trying "Maildoso". Has anyone here used it? Is it actually better than other tools?

"I tested a small batch first and results were comparable to our Google setup. Ended up moving more campaigns there because of the lower cost. That's a good strategy, buy small package and compare with your current setup" – I want to try Maildoso. What do you guys think about it?

🟢 Dynamic IP Rotation: We rotate your IP addresses in real-time – if an IP gets flagged or blacklisted, we instantly swap it for a clean one before your campaign takes a hit, ensuring your emails consistently land in the primary inbox rather than getting stuck in spam.
🟢 Self-Healing Rotation: An automated resting period for mailboxes every two weeks that clears provider flags and recovers reputation on autopilot.
🟢 Global Customer Domain Tracking: Proprietary technology that allows you to safely include links without compromising your sender reputation.
🟢 Automated Inbox Placement Tests: Free email deliverability infrastructure testing every three days for all mailboxes, giving you real-time visibility into your health.

🔴 Conservative Limits: We suggest sticking to 15 emails a day per box to keep your domains healthy for the long run.
🔴 Google/SMTP Focus: We do not support Microsoft 365/Outlook/Azure environments at this time.
🔴 Lack of built-in warmup. We do not have an integrated warm-up yet, but we are currently working on it.

Do not choose a provider just because they offer the cheapest inboxes. Cheap infrastructure always costs more in the long run. When your deliverability drops, you pay for it in three ways:

1. You burn expensive leads. Good B2B data costs money. If your emails land in the spam folder, you waste those leads. You pay for contacts who never even see your pitch.
2. You destroy your domains. Once spam filters flag a domain, it is incredibly hard to fix. You usually have to throw the domain away, buy a new one, and start the warm-up process all over again.
3. You lose revenue. Every email that goes to spam is a missed meeting. In B2B sales, missing one connection can cost you thousands of dollars in closed revenue.

You have to treat cold email infrastructure as an investment. Maildoso.ai gives you the technical tools to protect your domains and keep your emails in the primary inbox. It is the only way to scale outbound sales profitably.

We generally advise against using Sending.ac.

The issue isn’t necessarily with this specific product, but rather with Azure tenants as a whole. Despite their low cost, these accounts simply cannot send a sufficient volume of emails (only 2–4 per day). Furthermore, we frequently hear reports of Azure tenants being blacklisted by email service providers, often leading to a total infrastructure ban that forces the provider to shut down entirely.

If you don't currently have any mailboxes, it's better to start with more reliable providers like Maildoso, Zapmail, or Scaledmail. On the other hand, if you already have an established setup and are simply looking to experiment, there are other Azure tenant providers on the market offering much more flexible and affordable entry-level plans.