Hello, Ricardo! Thanks for the answer, I've found the cause of the bug. Firstly I've removed network-manager at all and filled files /etc/resolve.conf and /etc/network/interfaces. And claws-mail started in online mode! So, I've installed network-manager once again and compared debug information from claws-mail 3.7.8 and 3.7.10.
3.7.8 wrote the string: "main.c:921: NetworkManager" and started online. 3.7.10 wrote: "main.c:2791:NetworkManager: Went offline" and started offline (online mode worked after Ctrl+W only). All the settings were same and version of network-manager were 0.8.4. So, I've updated my network-manager to the version 0.9.0. And claws-mail 3.7.10 started online at my Debian! So the problem is with interaction of claws-mail 3.7.10 with old versions of network-manager. Claws-mail 3.7.8 and 3.7.9 worked well with network-manager 0.8.4 on Debian but version 3.7.10 needs network-manager 0.9.0 to start online automatically (without pressing Ctrl+W). With best wishes, Alaksiej. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]

