I have no support/technical question and have seen the support category. (Be aware that direct support questions will be deleted.)
on
Which general topic do you have
Let’s have a show of hands. Who is running Nextcloud Mail 5.7.0 successfully, as in something approximating the performance of Roundcube, and which setup are you running it on? I’ve been through a few configurations without success, but I’m new to Nextcloud, so I must be the problem. Therefore this is not a technical support question. I’m open to trying just about any version that I can run on an Ubuntu host: AIO, Docker, Snap, etc. Special thanks to anyone running it well behind HAProxy.
showing hands 
for the snap
bar having used roundcube no performance comparison possible… personally I’ve used snappymail which is, as the name suggests, really snappy! sadly development has slowed to a halt due to illness.
as far as the subjective performance of Nextcloud Mail 5.7.0 on Nextcloud snap latest is concerned, it takes getting used to, but its functional. there are some odd issues but its unclear if that’s just “teething” issues as they aren’t reproducible.
all in all, it may be slower than anticipated, but it works better than expected and its perfectly integrated.
Thanks for chiming in. Are you running it using the Let’s Encrypt setup or self certified? Do you have it behind a reverse proxy? Which version of Ubuntu (my assumption given you are running the snap)?
I started over with the the 31/stable channel snap on Ubuntu 24 LTS latest, which installs Mail 5.6.13. This is the most functional version that I have found. Quirky as you say, but usable for just checking incoming emails when not at my desk, where I have Thunderbird. It works the same from the local host using the IP address without https or with self certification behind HA Proxy with SSL passthrough.
I had my original setup, which used the Docker image, working nearly as well before I accepted the upgrade to Mail 5.7.0. I think I will make a go of this snap version with Mail 5.6.13 for the sake of my sanity until I have a comprehensive example of a Mail 5.7.0 setup that works.
Wow thanks for that link and all the effort that you have put into the snap version. I’ve managed to regroup now and redeploy all of the essentials plus Element and the AI Assistant on the 31/stable channel.
I’m still interested to hear from anyone else that has Mail 5.7.0 up and running well. At some point I will have to cross that bridge.