Category
Email Deliverability
Key features
Google Workspace and Microsoft 365 mailboxes
Domain purchase and management
Premium mixed mailbox pool
01 — Overview
What is
ColdSire
ColdSire provides cold email infrastructure: Google Workspace and Microsoft 365 mailboxes plus domains, set up in minutes for outbound sending. Mailboxes come from a premium pool shared with regular businesses rather than cold email only accounts, each domain gets its own isolated workspace with admin access, and SPF, DKIM, DMARC and forwarding are configured for you. Accounts connect in one click to sending tools like Instantly and Smartlead.
02 — Who it’s for
Ideal Customer Profile
Outbound sales teams and lead generation agencies that need many sending mailboxes for cold email. The site says 5,000+ companies and 500+ agencies use it.
03 — Capabilities
Key Features
Google Workspace and Microsoft 365 mailboxes
Domain purchase and management
Premium mixed mailbox pool
Per domain workspace isolation
Automatic SPF, DKIM and DMARC setup
Central mailbox and profile management
One click Instantly and Smartlead connection
05 — Similar tools
Alternatives
06 — FAQ
Frequently Asked Questions
What is ColdSire used for?
ColdSire is used to set up and manage the mailboxes and domains that cold email campaigns send from, configured for strong deliverability.
Who is ColdSire for?
Cold emailers, outbound sales teams and agencies that run high volume outreach across many inboxes.
Do I need to set up DNS authentication myself?
No. SPF, DKIM, DMARC and email forwarding come preconfigured, and display names and profile photos can be managed centrally.
Which sending tools does ColdSire work with?
Mailboxes connect with one click to Instantly and Smartlead, and the site says it works with other sending platforms too.