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Originally Posted by n5bb
The “X-Delivered-to” header shows the address used by Fastmail to find the delivery account using the aliases assigned to each account. If a “To” or “Cc” header includes your address, it is used to create “X-Delivered-to”. But if there are is no “To” or “Cc” header, the envelope address of the received message is used instead.
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My understanding is that “X-Delivered-to” is simply the original envelope recipient.
Quote:
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The “ X-Resolved-to” header shows the target delivery address assigned when the sieve script is executed.
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X-Resolved-to comes from taking the address in X-Delivered-to and iteratively following aliases targets and converting local sub-domains to plus-addressing. This has to be done fairly early so that an account can be indentified for per user features like Bayes.
Years ago FM used to deliver a single version of each email, so headers like X-Delivered-to could not be added if there were multiple local recipients. You had to use the combination ["x-delivered-to","Cc","To"] to maximize the number of correct matches and even then it wasn't fully reliable.
These days emails with multiple recipients are converted into separate instances, and X-Delivered-to is reliable. I just use that for the recipient address.
30 Jan 2021, 08:18 AM
