How can I remove the tabulator in the subject of e-mail notifications

Question

We use a self hosted JIRA 6.4.4 on Ubuntu 12.04. LTS. In all JIRA e-mail notifications there is a tabulator in the email subject. I can identify the tab character in the email header and I also see it in Outlook 2016 in the e-mail preview. The tab is also after a random amount of characters. The tabulator appears in TXT but also in HTML mails. I've tried searching how this might happen but I cannot find a solution to remove the tab char.

Has anyone might have an idea where to adjust that?

Johannes Schwanzer · Accepted Answer

If someone else is facing this problem: It has nothing to do with JIRA, the email handler on the server we are using seems to create that phenomenon.