About
Email tools split in two: some only inspect addresses, servers, or headers and never send mail; Outlook reading needs a refresh token you already authorized, and only for mailboxes you may access.
A practical order for delivery issues
Start with MX to see which host should receive mail, then SMTP Short Connection Test for port and STARTTLS, then header analysis for the Received chain. Gmail checking covers @gmail.com only, 10 addresses per run.
Safety boundary
SMTP tests use a short TCP session. Header analysis stays in the browser. Outlook tokens are used for the current request only. Do not paste someone else’s credentials.
It does not send real mail
Gmail checking, Domain MX Record Lookup, SMTP Short Connection Test, and header analysis never deliver a message for you. SMTP opens a short session to read the banner and STARTTLS. Outlook reading is the exception: it uses the refresh token you provide to fetch recent mail, so use it only on mailboxes you are allowed to access.
Related tools
Free email tools: bulk-check Gmail, test SMTP connectivity and STARTTLS, look up MX records, analyze headers, and read recent Outlook mail with a token you are authorized to use.