Problems
Is your problem not listed here? Report a new issue.
Do you have a question? See FAQ.
Check that you have Java installed.
If the program is not working correctly it is possible that there are some errors in the program or in your environment. You may run the program from the command line (advanced users) or simply look into the program log file and look for some errors.
If you think the problem is a program fault, please report an issue and attach your log file.
The program is developed primarily on Linux, which is the the recommended operating system for it.
First of all check whether the message can be sent over the web pages of that gateway (the gateway website can be seen in gateway tooltip, see picture below). If it can't be sent, the program can't work either, because it uses the web gateway internally. If it can be sent, report a new issue.
If you have a low-end computer switch the appearance to "System" or "Multiplatform" in the program settings.