Hello, @Cronmoax Thank you for reaching out, just to reassure everyone that although the time stamps in the inbox shown in GMT (UK) the messages are not delayed across time zones and there should be no delay in anyone sending or receiving messages. The system sends the messages instantly to the other member.
The inbox was designed to only show GMT when it was first set up as the company is UK-based, with lots of members now using it in many countries the team are looking at adding other timezones. So it is not a bug, it is an original design feature and there are no issues in the messages working as they should. @weirdholyman I will tag you here to help answer your question as well 
I just did a quick test and sent a message to one of my owners (I am USA-based) and it went straight through. There are no reported issues with messages being sent or received or any delay in sending them. Apologies if the times in the message being in GMT make it confusing. This thread might also help Hours-long lag on receiving messages and notifications
If anyone is experiencing any issues of this nature, outside of what I have described above please reach out to Membership Services at support@trustedhousesitters.com and they will be happy to look into it for you.
The inbox is being updated by a dedicated team and you can see more here:Messaging & Applications