Help my Mac's fan is getting crazy

After upgrading from Yosemite to El Capitan, the fan is constantly running.

Below is an excerpt of the Console log.

Many thanks for any advice.

Gérald

26/09/2016 19:52:57,300 com.apple.xpc.launchd[1] (org.postfix.master[18515]) Service exited with abnormal code: 1

26/09/2016 19:52:57,300 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.

26/09/2016 19:53:07,385 com.apple.xpc.launchd[1] (org.postfix.master[18708]) Service exited with abnormal code: 1

26/09/2016 19:53:07,385 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.

26/09/2016 19:53:12,935 com.apple.CDScheduler[45] SysAdmChk: Throttling activity execution. memFlags:0x0 thermalLevel:0x1

26/09/2016 19:53:12,936 com.apple.CDScheduler[45] SysAdmChk: Throttling activity execution. memFlags:0x0 thermalLevel:0x1

26/09/2016 19:53:13,477 Console[18843] Failed to connect (_consoleX) outlet from (NSApplication) to (ConsoleX): missing setter or instance variable

26/09/2016 19:53:17,458 com.apple.xpc.launchd[1] (org.postfix.master[18899]) Service exited with abnormal code: 1

26/09/2016 19:53:17,458 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.

26/09/2016 19:53:22,351 com.apple.xpc.launchd[1] (com.apple.screensharing[19013]) Endpoint has been activated through legacy launch(3) APIs. Please switch to XPC or bootstrap_check_in(): com.apple.screensharing.server

26/09/2016 19:53:27,532 com.apple.xpc.launchd[1] (org.postfix.master[19096]) Service exited with abnormal code: 1

26/09/2016 19:53:27,532 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.

26/09/2016 19:53:29,234 com.apple.CDScheduler[45] SysAdmChk: Throttling activity execution. memFlags:0x0 thermalLevel:0x1

26/09/2016 19:53:29,236 com.apple.CDScheduler[45] SysAdmChk: Throttling activity execution. memFlags:0x0 thermalLevel:0x1

26/09/2016 19:53:37,598 com.apple.xpc.launchd[1] (org.postfix.master[19290]) Service exited with abnormal code: 1

26/09/2016 19:53:37,598 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.

26/09/2016 19:53:47,681 com.apple.xpc.launchd[1] (org.postfix.master[19484]) Service exited with abnormal code: 1

26/09/2016 19:53:47,681 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.

26/09/2016 19:53:57,755 com.apple.xpc.launchd[1] (org.postfix.master[19679]) Service exited with abnormal code: 1

26/09/2016 19:53:57,756 com.apple.xpc.launchd[1] (org.postfix.master) Service only ran for 1 seconds. Pushing respawn out by 9 seconds.