Unable to send multiple headers with same key, but different value

[iand675]

I'm trying to set multiple tags in mailgun using the X-Mailgun-Tag header, and it expects each tag to be sent in a different header.

Since maps only allow one value per key, it would be nice to maybe support seqs as values in the message map for extra headers, e.g.:

{ "X-Mailgun-Tag" ["foo" "bar"] }

Ideally this would add a header for each value in the seq.

[osbert]

Please see this commit/branch if you still would like to be able to do this:

https://github.com/osbert/postal/tree/allow-header-splitting