Best Email Infrastructure to Power Your Instantly Campaigns

Maildoso is one of the most popular infrastructure providers among Instantly users, thanks to its one-click Instantly integration that exports mailboxes directly into your Instantly account. Managing 400,000+ mailboxes and 10 million+ daily emails, Maildoso offers both SMTP-only and SMTP+Google Workspace Combo plans at the cheapest bulk pricing in the market.

SMTP pricing scales with volume: 30 for $75/month ($2.99/mb), 300 for $570 ($1.90/mb), and 10,000 for $12,000 ($1.20/mb). Combo plans start at $3/mb for 15+15 (SMTP+GW). The one-click Instantly export eliminates manual IMAP/SMTP configuration — mailboxes appear in your Instantly account automatically. G2 4.7 from 159 reviews, 5,000+ companies.

The main trade-off is that SMTP mailboxes are not real Google or Microsoft accounts, which can affect deliverability to certain ESPs. There is no domain monitoring or blacklist checking, so you will not get proactive alerts about deliverability issues. For Instantly users who prioritize the cheapest possible infrastructure with seamless integration, Maildoso is the leading choice.

Mailforge offers the cheapest per-mailbox pricing for Instantly users through shared-IP SMTP infrastructure. Part of the Salesforge ecosystem, it provisions mailboxes in about 5 minutes with automated DNS and generates SMTP credentials that connect to Instantly via standard IMAP/SMTP configuration. The platform serves 10,000+ businesses with a 4.9 rating.

Pricing is $3/mailbox/month on monthly billing or $2/mailbox/month on annual, with a 10-mailbox minimum. Unlike Maildoso's one-click Instantly integration, Mailforge requires manual SMTP/IMAP credential entry to connect to Instantly. Features include automated DNS, SSL, domain masking, and multi-workspace support.

Mailforge is the lowest-cost option for powering Instantly campaigns, but the shared-IP infrastructure and lack of real Google/Microsoft accounts can limit deliverability. There is no built-in warmup (Instantly's warmup pool covers this) or monitoring. For budget-conscious Instantly users running high-volume campaigns where per-mailbox cost is the primary concern, Mailforge delivers at $2/mo annual.

Primeforge provides real Google Workspace and Microsoft 365 accounts from the Salesforge ecosystem, offering Instantly users actual ESP accounts rather than shared-IP SMTP. Mailboxes come pre-warmed with profile pictures and GIFs configured at scale, plus ESP matching that assigns the right account type based on your prospect's email provider.

Pricing is $4.50/mailbox/month on monthly billing or $3.50/mailbox/month on annual, with a 10-mailbox minimum. This is higher than InboxKit's $2.50/mo for Google Workspace, but Primeforge includes pre-warming and ESP matching in the base price. Connection to Instantly is via standard IMAP/SMTP credentials and app passwords.

For Instantly users who specifically want real Google and Microsoft accounts with pre-warming already done, Primeforge delivers a higher-quality mailbox than Mailforge or Maildoso's SMTP. The trade-off is cost — at $3.50/mo it is 40% more expensive than InboxKit for the same account type. Monitoring requires the separate Infraforge product, and the multi-product Salesforge ecosystem adds complexity.

Inframail offers unlimited Microsoft inboxes at a flat monthly rate with built-in Instantly export functionality, making it appealing for Instantly users who run high-volume Microsoft-based campaigns. The Unlimited Plan includes a dedicated US IP with auto-export to Instantly — mailboxes appear in your Instantly account without manual credential entry.

The Unlimited Plan costs $129/month (1 dedicated US IP, 80,000 emails/mo) and the Agency Plan costs $327/month (3 dedicated IPs, 300,000 emails/mo). At 100+ inboxes, Inframail's effective per-inbox cost drops well below $1.30 — significantly cheaper than per-mailbox providers at scale. Features include Phantom Redirect and auto blacklist delisting (68.3% success rate). 2,000+ B2B companies, 4.8/5 rating.

The main limitation for Instantly users is Microsoft-only infrastructure — no Google Workspace accounts. Teams running Google-focused Instantly campaigns need a different provider. The $129/mo minimum is also expensive for smaller Instantly users. But for agencies running 100+ Microsoft mailboxes through Instantly, Inframail's flat rate with auto-export is hard to beat on cost.

Hypertide provisions Google Workspace, Microsoft 365, and Microsoft Entra accounts with direct Instantly auto-linking at $50/month per order of 50 inboxes. Designed as a VA replacement, Hypertide automates the entire mailbox creation process and links accounts directly to your Instantly dashboard in 4-6 hours.

At $1/inbox effective rate, Hypertide is one of the cheapest ways to get real Google and Microsoft accounts into Instantly. Each order is isolated in its own tenant, reducing cross-contamination risk. The direct Instantly integration means no manual SMTP/IMAP configuration — accounts appear in Instantly automatically.

The main limitations for Instantly users are the 50-inbox cap per order and 5,000 emails/month sending limit. High-volume Instantly campaigns may require multiple orders, and the 5,000 email cap per order may not match your campaign volume needs. There is also no monitoring, warmup (you would rely on Instantly's warmup pool), or inbox placement testing. For budget Instantly users who need real accounts in small batches, Hypertide delivers at an unbeatable price.