Understanding the “handshake” between your server and the recipient’s server is the key to solving email sending problems.
See the exact server conversation to find out why your emails aren’t sending. Instantly identify authentication issues, port blocks, or server rejections.
Before plugging new SMTP settings into your app or plugin, confirm your server, port, username, and password are all correct in a safe, isolated environment.
Ensure your server is reachable on the correct port (like 587, 465, or 2525) and that your chosen security protocol (TLS, SSL, or None) is properly configured.
Switching to SendGrid, Mailgun, or Amazon SES? Use this tool to get a detailed, raw log of your first connection attempt to ensure your setup is perfect.
This is the most common success code. You’ll see it after a successful connection, when the ‘FROM’ and ‘TO’ addresses are accepted, and when the email is queued.
This error means your username or password is incorrect. Check your credentials, make sure you’re using the right API key or password, and try again.
This means the tool couldn’t reach your server. This is almost always a sign of an incorrect server address, a blocked port by your firewall, or the wrong port number.
This indicates a mismatch in security protocols. You might be trying a TLS connection on an SSL-only port (like 465) or vice versa. Check your port and security setting.
A successful connection is just the first step. Warmup Inbox builds a powerful sender reputation for you, ensuring your most important emails always land in the inbox.