InboxKit or Maildoso: Which One Should You Pick?

InboxKit vs Maildoso

Feature	InboxKit	Maildoso
Pricing
Price per Mailbox	$3.10-$2.50 by tier Three tiers to choose from: Professional at $31/mo for 10 slots ($3.10 each), Agency at $81/mo for 30 slots ($2.70 each), Enterprise at $250/mo for 100 slots ($2.50 each). Warmup adds $3 per mailbox on top.	$1.90-$2.50/mo Pure SMTP starts at $1.90; the SMTP-plus-Google-Workspace Combo option runs $2-$3/mo.
Infrastructure
Mailbox Types	GWS + M365 + Azure All three of Google Workspace, Microsoft 365, and Azure are on the table.	SMTP + Combo Choose plain SMTP or the Combo tier that layers in Google Workspace.
IP Location	US IPs Every mailbox sends from a US-based IP.	Not specified Where the IP is located depends on which mailbox type you pick.
DNS Automation	Full auto SPF, DKIM, DMARC, and MX all configure themselves.	Auto DNS DNS configuration is automated out of the box.
Deliverability
Inbox Placement Rate	95% claimed Claims a 95 percent placement rate across every mailbox type it offers.	Not published Doesn't publish a placement-rate figure.
Built-in Warmup	Yes Warmup lives inside the infrastructure layer itself.	No You'll need to source warmup from your sending tool instead.
Inbox Placement Testing	Yes Lets you check whether a send actually lands in the inbox or the spam folder.	No Not offered — route this through your sending platform instead.
Email Verifier	Yes Verification is built directly into the platform.	No No native verifier is offered.
Blacklist Checker	Yes Keeps an eye on IPs and domains against known blacklists.	No Not built in natively.
Scale
Scale Track Record	Enterprise clients Counts 11x, Zendesk, PwC, and Merck among its customers.	400K+ mailboxes Runs 400,000-plus mailboxes and pushes over 10 million emails a day.
Social Proof
G2 Rating	Not listed No G2 rating on record.	4.7 (159 reviews) Sits at 4.7 out of 5 across 159 verified G2 reviews.
Automation
API Access	Yes API access supports automated mailbox provisioning.	Yes + MCP Offers both API and MCP support for automation.

Infrastructure and Mailbox Types

Mailbox variety is where these two diverge most. InboxKit houses Google Workspace, Microsoft 365, and Azure mailboxes under a single account, which means you can experiment to see which provider actually delivers best for a given domain and audience. Maildoso, by contrast, is built around SMTP, with a Combo tier available if you want Google Workspace layered on top.

Google Workspace mailboxes tend to land in the inbox more reliably than SMTP for cold outreach, and InboxKit hands you that option from the first mailbox you provision. Maildoso makes up the difference with a lower price and a scale record to match — 400,000-plus mailboxes under management and over 10 million emails processed daily.

Deliverability Tools

InboxKit folds an entire deliverability toolkit into its infrastructure layer — warmup, placement testing, verification, blacklist monitoring, all of it. That's not typical; most competitors, Maildoso included, push deliverability responsibility onto whatever sending tool you use. Maildoso genuinely ships none of those: no warmup, no verifier, no placement testing.

You'll be sourcing all of it from Sendbox or a comparable platform. Teams already running Sendbox (which covers each of those bases) won't notice the gap. Teams that specifically want deliverability monitoring living at the infrastructure level, though, have only one real option here, and it's InboxKit.

InboxKit vs Maildoso: Cost at 100+ Mailboxes

Line up 100 mailboxes on each and InboxKit's Enterprise tier lands at $250/mo flat (the included 100-slot rate of $2.50 apiece). Maildoso's SMTP fleet runs $190 to $250/mo at that same count, and the Combo tier with Google Workspace pushes it to $200-$300/mo. At 100 mailboxes, the base bills are genuinely close.

Two things belong in the real math, though: InboxKit's Email Warmup is a separate $3-per-mailbox add-on (another $300/mo at this scale), but it also throws in the verifier, placement testing, and blacklist checker that Maildoso doesn't offer at any price. And at smaller counts — the 10 to 30 mailbox range — InboxKit's Professional and Agency tiers charge $3.10 and $2.70 per mailbox respectively, not the $2.50 headline rate, so plan your budget around the tier you'll actually land in.

InboxKit vs Maildoso: Which One Fits Your Use Case

InboxKit makes sense if you'd rather have one provider handle mailbox provisioning, DNS, and the full monitoring stack — verifier, placement testing, blacklist checker — right out of the base tier. Rates run $3.10 on Professional, $2.70 on Agency, and $2.50 on Enterprise, with Warmup priced separately at $3 per mailbox. It also wins on mailbox variety, spanning Google Workspace, Microsoft 365, and Azure.

Maildoso is the better call if raw per-mailbox cost is what matters most and you're already running Sendbox or another platform that handles warmup for you. Its 400,000+ mailbox track record and category-leading G2 reviews back up the price. Either way, both connect into Sendbox for campaign management, sequencing, and AI warmup.