Setting Up Mailboxes for Cold Email

Choosing an email provider for cold outreach

Not all email providers are equal for cold outreach. The key factors are: deliverability reputation (do emails from this provider tend to land in inbox?), sending limits (how many emails per day does the provider allow?), SMTP access (can you connect a third-party sending tool?), and cost per mailbox.

Google Workspace and Outlook (Microsoft 365) have the best deliverability reputation — receiving servers trust mail from these platforms. Zoho Mail is a cost-effective alternative. Free providers (Gmail.com, Outlook.com) are not suitable for cold outreach — they're flagged more easily and have strict anti-spam enforcement.

• Google Workspace is the gold standard for cold outreach deliverability.
• Zoho is excellent for startups on a budget — good reputation and cheap.
• Microsoft 365 has higher daily limits but Outlook-to-Outlook deliverability can be quirky.

Provider comparison: Google Workspace: Best deliverability, $6/mailbox/month, 2,000/day limit Microsoft 365: Excellent deliverability, $6/mailbox/month, 10,000/day limit Zoho Mail: Good deliverability, free–$1/mailbox/month, 500/day limit Fastmail: Good deliverability, $5/mailbox/month, custom limits Avoid: Gmail.com, Outlook.com (free) — these are for personal use, not outreach.

Mailbox configuration for maximum deliverability

After creating a mailbox: complete the profile (add a real first name, last name, and profile picture). Set up a professional email signature (name, title, company, phone). Configure the sending name as 'First Last' not just the email address. Enable two-factor authentication (for security, not deliverability). Connect the mailbox to your cold email tool via SMTP/IMAP.

A mailbox that looks like a real person — with a filled-out profile and a human signature — performs significantly better than a bare email address. Inbox providers use account age, profile completeness, and sending patterns to determine trust.

• Use a real person's name and photo on the mailbox — even for a team email account.
• Signature: name, title, company name, phone number. No images, no HTML.
• Keep the same name across Google Workspace and LinkedIn — consistency builds credibility.

Daily sending limits per mailbox

Sending limits exist at two levels: provider limits (the hard caps imposed by your email provider) and deliverability limits (the recommended maximum for maintaining good reputation). The deliverability limit is always lower than the provider limit.

For cold email, the recommended limit is 300–500 emails per day per mailbox, regardless of what the provider technically allows. Sending 1,500 emails per day from a Google Workspace account (technically within the 2,000/day limit) will damage your reputation quickly because the volume pattern triggers automated spam filters.

• Add a 60–120 second random delay between emails — reduces pattern detection by spam filters.
• Never send more than 60–70% of your provider's daily limit.
• Split high-volume campaigns across multiple mailboxes rather than pushing one to its limit.

Recommended vs provider limits: Google Workspace: Provider limit 2,000/day → Use max 300–500/day for cold Microsoft 365: Provider limit 10,000/day → Use max 400–600/day for cold Zoho Mail: Provider limit 500/day → Use max 200–300/day for cold

How many mailboxes do you need?

Calculate based on your daily volume target. If you need 1,000 outreach emails per day, and each mailbox sends a maximum of 300 cold emails per day, you need at least 4 mailboxes — ideally across 2–3 different domains for additional resilience.

For a small team (one SDR or founder doing their own outreach): 1–2 mailboxes across 1–2 domains is sufficient. For a 3–5 person SDR team: 6–10 mailboxes across 3–5 domains. For a larger team: the math scales linearly — add one mailbox per 300 daily emails needed.

• Distribute mailboxes across 2–3 domains — so if one domain gets flagged, others continue.
• Use real names: john@mailmaya.in, priya@mail.mailmaya.com, rajan@getmailmaya.com
• Warm each mailbox independently — don't share warm-up sessions across mailboxes.

Maintaining healthy mailboxes over time

Mailbox health is not a set-and-forget task. Monitor bounce rates weekly (target under 2%), track spam complaint rates (target under 0.1%), and review any unusual sending activity. Pause a mailbox immediately if you see spam complaint rates rising — investigate and fix before resuming.

Every 6–12 months, rotate your DKIM keys and review your SPF record for services you may have added or removed. Review your sending domains' reputation in Google Postmaster Tools monthly. A mailbox that's consistently clean for 12+ months has a strong enough reputation cushion to survive occasional bumps.

• Set calendar reminders to check Google Postmaster Tools monthly.
• A bounce rate spike (suddenly 5–10%) often means your list quality has dropped — clean the list, not the mailbox.
• If a mailbox gets suspended by the provider, investigate why before creating a replacement.