Custom Headers
Adding, changing and removing headers on the mail you send.
What Headers Are
Every email carries a block of headers above the text: the familiar From, To, Date and Subject, and many you never see. Mail programs add their own, and some of them are chatty: the program's name and version, the sender's IP address, the time zone, the mail path. CodaMail already removes the identifying ones from everything you send, through the webmail or a mail program. These two pages are for people who want to go further or add their own.
Add or Change Headers
Settings → Add/Change Headers lets you add a header, or replace the value of one your mail program sets, on every outgoing message. Enter the Header Name and Header Value and click Add; names use letters, digits, dots and hyphens, and a short list of structural headers (From, To, Date and the like) cannot be touched. A common use is setting a fixed, generic User-Agent so every message looks the same regardless of which device sent it. Delete an entry to stop adding it.
Remove Headers
Settings → Remove Headers shows the list of headers CodaMail can strip from your outgoing mail. With nothing ticked, every header on the list is removed, which is the default behaviour. Tick specific ones to remove only those and let the rest through; tick only Do_Not_Remove_Any_Headers to let all of them through. Most people never need to change this page: the default removes everything on the list, which is the private choice.
The list covers the headers that name your software or machine: User-Agent, X-Mailer, Mailer, X-MimeOLE, X-Newsreader, X-Originating-IP, X-Sender, X-X-Sender, Sender, Organization and Organisation, Phone, Fax and Telefax, Complaints-To and X-Complaints-To, Version and Mail-System-Version, Originating-Client, X-HTTP-UserAgent, X-Enigmail-Version, X-Priority and X-MSMail-Priority, X-Trace, X-Virus-Scanned, X-Account-Key, the Mozilla status and keyword headers, the Mailtags headers, X-Smtp-Server and X-Readdle-Message-ID.