SDRclose Blog
Deliverability articles from the SDRclose team: practical, tested advice for outbound sales teams.
Google Workspace leads on measured reply rate, Microsoft 365 suits Microsoft-heavy lists, and the cold email community warns hard against Zoho. Here is the data behind each verdict, plus the SMTP, IMAP and DNS setup.
A new mailbox on an aged domain needs two to four weeks. A brand new domain needs four to eight, and 30 days is the floor most 2026 guidance now uses. Here is the schedule and the stop signal.
Operators quote 15, 30 to 50 and 100 a day per inbox, and all three can be right. Here is what the 2026 datasets show, where the provider ceilings sit, and how to size inboxes and domains for your target.
Authentication passes and placement is still broken. Here are the seven causes that survive a clean SPF, DKIM and DMARC setup, the test that identifies each one, and the order to work through them.