[exim] Advanced Exim Configuration with the smart_route dire…

Trying this one more time as I do not think my first send registered.
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Hello!

I am trying to configure Exim's smart_route directive to only apply when
the mail is sent via PHP's mail() function. The mail relay works as
expected but currently it routes both webmail and phpmail when I only
want it to do the latter. I looked into the 'condition = ' flag but
couldn't find anything specific for this issue. Is what I am looking to
do possible? Should I be asking somewhere else? Below is my smart_route
config (under the 'Section: ROUTERSTART' in Advanced Editor of exim
configuration manager):

smart_route:
driver = manualroute
domains = !+local_domains
transport = remote_smtp
route_list = * 10.10.15.107

I might want to attack this from a different direction if the former
doesn't work. I've set php mail to send via port 587 with the smtp_port
php.ini directive. Is there any way I can set the Exim smart_route
option with a condition to only apply to port 587?

Thank you,
Danielle M.