How to launch PA Thunderbird in "Offline Mode"? No Profile Manager possible

(1) In an open instance of Thunderbird and assuming you what to launch Thunderbird in Offline mode, do the following:

(2) Go (menu) Tools > Options > General > Network & Disk Space > Offline... (button) (click on the button, a dialogue GUI will open up). (NOTE: you need to scroll down the General page to get to the Network & Disk Space options.)

(3) In the GUI look for the entry titled Manual state when starting up: select Offline then OK the dialogue. (NOTE: you can experiment with some of the other settings later to see if they offer anything that might be more useful to you.)

(4) Shut down Thunderbird and then relaunch it. It should now start up in Offline mode.

Lastly, in theory it should be possible to start Thunderbird in offline mode without making any of the above settings. For suggestions on that drill to the following folder in your Thunderbird Portable 'install' folder (you will need to adjust the path to suit what actually exists on your own system. E:\ThunderbirdPortable\Other\Source In that 'Source' folder you will find a Readme.txt file. Open that file and you will see instructions on what in can be done with the AdditionalParameters= option -- but I tried passing the "-p" parameter following the instructions and it didn't work on my system. Maybe John will come along and comment on why that isn't working. In any case, if you want to experiment with that you will need to make a copy of the file ThunderbirdPortable.ini into the appropriate folder on your system -- the instructions on where to place the 'ini' file are in the Readme.txt file.

Hope this helps.

EDIT: P.S. I do see the setting in the Offline Settings GUI that says Automatically follow detected online state. I don't know what that tick-box setting is for. I could not find up-to-date information on the setting on the web. However, I did find some older information on the web for that setting for (much) older versions of Thunderbird. It seemed that the general advice was to untick that setting and then select whatever of the Manual state when starting up: options that you want to enforce. So, if it was me, I'd experiment a bit with ticking/unticking the setting for "Automatically follow detected online state" and see what, if any, difference it makes to the other "Manual. . . " settings. I tried a quick experiment and couldn't see any difference if the tick-box was just left ticked (which seems to be the default setting).

EDIT 2: Found the appropriate information for the Manual state when starting up:. The information can be seen here: https://support.mozilla.org/en-US/kb/advanced-panel-settings-in-thunderb... (Much clearer now.)

Profile manager only works with local profiles. This is by design of the publisher. You can't use it with Thunderbird Portable.

You can either set Thunderbird to always start in Offline mode using the method you mentioned in the settings or start it with the -offline switch. This can be fed to ThunderbirdPortable.exe if you're starting it from a shortcut. You can also copy the ThunderbirdPortable.ini file from the ThunderbirdPortable\Other\Source directory to the ThunderbirdPortable directory and set AdditionalParameters=-offline