How to reproduce:

• Create a mail filter in Preferences -> Mail
• Check that the sieve script exists on the imap server
• Activate the mail transfert to an invalid address (ex: "invalid,address@x.com") yes, that's a comma...
• Check the sieve script on the imap server, it is nowhere to be seen
• Disabling the mail transfert makes the original filter work again.

Logs:

Jun 30 11:28:32 sogod: SOGo watchdog [9422]: [ERROR] <0x0815D750[SOGoMailAccount]:marmotte_D_jean_A_test_D_com> Could not upload Sieve script: {RawResponse = "{ok = NO; reason = \"script errors:
line 2: address 'invalid,address@x.com': syntax error, unexpected $undefined, e\"; }"; result = NO; }

Some error handling / input validation might be required here.