How to get IPv6 in exim env?

Question

Exim

Hello!
I pass a variable to the script like this:

mytransport:
driver = pipe
command = /path/to/script
environment = SENDER_HOST_ADDRESS=$sender_host_address

If the host is ipv4 there is no problem, but if the host is IPv6 - only the first octet is assigned to the variable (before the first character ":"). The reason is the colon separation of environment in Exim . How can this be defeated (except for the option of passing it as an argument to the script).