On 18 Nov 2015, at 12:36, Sergey Dorofeev <sergey@???> wrote: > there is no additional software, just "verify = header_syntax" in acl_check_data.
> If this syntax is really invalid, then I should consider it as flaw of libreoffice-users mailing list.
verify = header_syntax will cause the error message (and rejection) you're seeing.
This isn't a flaw of that mailing list; it's a flaw of the message originator's MUA - it isn't adhering to the RFCs as the name part there should be quoted, as Mike states. The intervening MTAs simply aren't being as strict as you, passing as they are the original message unedited (which is what they're supposed to do).
I'd review your logs over whatever period you have available and see how many emails are being rejected as a result. If it's only one sender, and only one mailing list, you could consider removing that check in your DATA ACL.
