ISPConfig stopped sending emails

Hello,
some time ago ISPConfig stopped sending emails with quota warnings. I checked /var/log/ispconfig/cron.log and there are multiple error lines:

Code:

Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694
Wed Sep 23 00:35:22 CEST 2015 PHP Warning:  mail(): Multiple or malformed newlines found in additional_header in /usr/local/ispconfig/server/cron_daily.php on line 694

Thanks for any idea how to fix it.

 

Hi Till,
thank you for replay. Mail sending works again but there is one problem. In text of the mail is missing space between lines. Now the text is confusing. Is there a way how to keep empty lines? Is it possible to use html mail?
Thank you.

 

Thank you till. I temporary solved it by adding dots to empty lines