Category
Deliverability
Domains, mailboxes, pacing and the signals providers actually read.
Deliverability · 7 min read
Bounce codes explained: what 550, 551 and 552 actually mean
A cold email bounces and the reason lists a number like 550 or 552. Here is what that code means, what counts as a hard bounce, and when to act.
Deliverability · 7 min read
Should you send cold email from your main domain or a separate one
Your domain is the unit of reputation. Here is what a separate sending domain protects, what it costs you in trust, and how to set one up so it does more good than harm.
Deliverability · 7 min read
Open rates after Apple Mail Privacy Protection: what they still tell you
Apple Mail fetches every tracking pixel whether or not a message is read, so open counts are inflated. Which comparisons survive, and what to watch instead.
Deliverability · 7 min read
Mailbox rotation explained: how one campaign sends from many addresses
Rotation spreads a campaign across several mailboxes so each one stays under its own limit, while every prospect keeps talking to the same person in one thread.
Deliverability · 7 min read
What bounce rate is safe for cold email, and what to do when it rises
Why no provider publishes a safe bounce number, which kinds of bounce matter most, and how to set a threshold that stops a campaign before your domain pays for it.
Deliverability · 7 min read
SPF, DKIM and DMARC for cold email senders, explained without jargon
What the three authentication records do, why cold email domains break them more often than others, and how to check that yours pass before a campaign starts.
Deliverability · 7 min read
Cold email daily sending limits: how many messages per mailbox
The provider cap is not the number that matters. How to set a daily limit per mailbox that keeps cold email out of spam, and how to grow volume without raising it.