Straight answers, no scare tactics.

Up to 10, and that's a hard ceiling. We'd rather add domains than crowd more inboxes onto one reputation-bearing asset.

The domain carries the reputation. The more sending you pile onto one domain, the more a single bad signal can drag everything on it down. Low density keeps headroom and protects the client.

Provisioning is automated. For standard fresh infrastructure, order to mailbox access is generally a couple of hours or less.

Both. Bring your own domains, or have Mailrun manage them. Deployments that require us to buy more than 40 domains are mapped on a short planning call so cost and timing are confirmed up front.

Prepared inventory for agencies that need a faster client launch path. Pre-warmed domains start at $19 per domain per month and include 5 inboxes each, with a 10-domain minimum. Purchase directly while inventory is available. Larger or custom deployments may require a short planning call.

Different model, built for a different operating assumption. Mailrun is Microsoft / Azure infrastructure with low domain density, horizontal scale, automated provisioning, and a clear operating lifecycle — built for agencies that care about durable client sending, not the lowest possible mailbox price.

Mailrun does not impose a 5-email daily cap. We recommend sending no more than 5 campaign emails per inbox every 24 hours, spaced throughout the day, with warm-up activity handled separately. This is an observed safe operating threshold intended to help keep inboxes healthy—not a platform limit or a guarantee of deliverability. When you need more volume, the safer approach is usually to add inboxes and domains rather than push each inbox harder.

For fresh infrastructure, two weeks is the minimum ramp we recommend, while three to four weeks provides a more comfortable runway. The right timeline depends on the age of the domain, planned volume, list quality, and early sending signals. Pre-warmed infrastructure can begin controlled campaign sending on day one, with volume increasing gradually based on performance.

No. You need to keep warm-up running after campaign sending begins. Warm-up is one part of an ongoing operating process that also includes controlled volume, list quality, bounce monitoring, and domain management.

We generally recommend leaving open and click tracking off for outbound campaigns. Tracking pixels and rewritten links introduce additional technical variables, while open data is increasingly unreliable because privacy features and security gateways can record activity that did not come from the recipient. Replies, bounces, and qualified conversations are usually more useful operating signals.

Mailbox providers evaluate many signals, including sending patterns, domain history, authentication, bounce and complaint activity, message content, and recipient engagement. Mailrun reduces avoidable risk through controlled sending volume, authenticated infrastructure, low inbox density, clean recipient data, and ongoing domain monitoring. No provider can guarantee inbox placement, but disciplined operations can reduce the signals associated with bulk or abusive sending.

Bounce rates below 2% are good. A clean list can get bounce rates under 0.5%. A sustained increase in bounces is a signal to pause, review the list and sending configuration, and correct the underlying issue before increasing volume.

Domain performance can change over time as sending volume, recipient quality, complaints, and engagement patterns change. Mailrun uses rotation so a campaign does not depend indefinitely on one domain. Domains can be kept active, rested, reviewed, or replaced based on observed health signals rather than a fixed expiration date.

We generally recommend .com domains because they are familiar to recipients and tend to look more credible in business communication. Other extensions can work, but the choice should consider brand fit, recipient expectations, availability, and observed campaign performance. The domain extension alone does not determine deliverability.

At an operating target of 5 campaign emails per inbox across approximately 22 sending days, one inbox provides about 110 campaign emails per month. That means 100 inboxes provides roughly 11,000 monthly sends, while 200 inboxes provides roughly 22,000. Standard Mailrun infrastructure supports up to 10 inboxes per domain; pre-warmed infrastructure currently includes 5 inboxes per domain. We size the setup around your target volume, timeline, and preferred operating headroom.

Mailrun operates on Microsoft Azure infrastructure. We manage provisioning, domain authentication, inbox density, sequencer handoff, and the operating lifecycle around the infrastructure. Mailrun is an independent service and is not sponsored or endorsed by Microsoft.

For supported sequencers, Mailrun can push inboxes directly into your workspace. For other platforms, we provide sequencer-ready files containing the required connection details, including SMTP and IMAP configuration. The exact handoff depends on the sequencer and the level of access you provide.

Replies are received by the sending inbox and normally appear in your sequencer’s unified inbox or reply-management view. When responding, use the same sending address that originally contacted the recipient. Keeping the conversation on the original sending identity avoids confusion and keeps your primary company domain separate from outbound campaign activity.

Yes. Verification results can become outdated as addresses change, mailboxes are disabled, and company data ages. Lists should be cleaned before a new campaign and reviewed again when they have been stored, modified, or sourced from multiple systems. If Mailrun is managing the campaign, list-cleaning responsibilities and the verification process are defined as part of that engagement.

Mailrun plans are month-to-month with no long-term commitment. You can cancel at any time, with cancellation taking effect according to the billing and cancellation terms presented during checkout.