[exim] host expansion variable and its friends

Does the $host expansion include the port, if present?

For instance, if I have

# ROUTERS

smarthost:
driver = manualroute
route_list = * mail.example.com::587
domains = ! +local_domains
transport = remote_smtp

# TRANSPORTS

remote_smtp:
headers_add = "X-Show-Host: $host"
driver = smtp

what will the inserted header say:

X-Show-Host: mail.example.com

or

X-Show-Host: mail.example.com:587

or even

X-Show-Host: mail.example.com::587

?

If the port is _not_ part of the expansion, is there any other way to
get at it within transport options?

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