Idk, I have things a little different I think.
My T lets me contact her outside of our appointments without any hesitation, but I have my own boundaries set up.
I have my iPod touch by my bed so if I have any ongoing thoughts at night that I can't get out of my head, I jot them down on the notepad in that and then roll over and sleep.
If anything comes up during the day, I write it down when I can think straight enough. Sometimes I write nothing more than just a few key words.

I e-mail things to her that are unrelated to what I'm actually seeing her for, but that's because she likes it when I'm comfortable enough to share things such as my art. Or when I made the leap and contacted someone finally, after spending a few weeks building up to it.
I have emailed her before when I had a rough day and I just needed to be heard, and possibly talk about it in next session.
She's allowed me to text if I ever needed her, and I have taken her up on that offer once when I was in emergency mode mentally. I was at my boyfriend's parent's house and his stepdad got drunk and angry, and I got super panicked and couldn't react appropriately, and I felt like I was in danger. She helped me 'dial down' emotionally and listed a few possible options that would help get me out of that situation, things I couldn't think of myself at the time because I wasn't thinking clearly.

Once I brought up that I was afraid of going 'off topic' in session because I thought I *needed* something to talk about, something important. She reminded me that this isnt school, and we're able to talk about anything that pops into mind if I want. Hell we've even had discussions on favorite cleaning products. rofl