Insights on cold email, deliverability, and scaling your outreach infrastructure.
An email list cleaning checklist for cold senders: dedupe, verify, strip role and disposable addresses, and suppress. Keep complaints under Gmail's 0.3% line.
A hard bounce is a permanent 5.x.x SMTP failure you must suppress now; a soft bounce is a temporary 4.x.x error worth retrying. Here's how to handle each.
Reduce your email bounce rate with 9 tactics beyond list cleaning: authentication, warmup, throttling, and soft-bounce retry logic that retries up to 5 days.
A catch-all domain accepts every address, so verifiers can't confirm it. About 38% of domains are accept-all and they bounce ~27x more.
Verify email addresses before sending with four checks: syntax, MX lookup, an SMTP RCPT probe, and risk flags. Read every verdict and keep bounces under 2%.
How many sending domains do you need for cold email? Size it from volume with the safe 2-3 mailboxes-per-domain ratio. A 10,000/month team needs about 6-9.
Calculate how many email accounts you need for cold outreach: divide your monthly target by a safe 25-40 sends per warmed mailbox.
Exchange Online caps every mailbox at 30 messages per minute. Here's how to set per-mailbox throttle, send spacing, and ramp settings for safe cold email.
How to connect a custom SMTP server to your cold email tool: host, port 587 vs 465, TLS, and auth, plus the BYO-relay deliverability traps that hurt placement.
