- Plesk Onyx for Linux
When sending emails to mail list created in Mailman, there are some additional tabulation symbols or whitespaces appear in email subject header.
Why does it happen?
There are mail agents which still insert an extra tabulation symbol or space when folding email subject. Also, there are mail agents which remove the whitespace character in a folded header, even though this is a violation of the RFCs.
Such behavior is not related to Plesk and Mailman: it describes how folding/unfolding is done in the underlying Python email package.