[ClusterLabs] FYI: users being automatically unsubscribed from list and/or not getting messages

[Ken Gaillot]

Hi all,

TL;DR if you've been having problems, they hopefully will get better
now


We have gotten some reports of users being automatically unsubscribed
from this list, or not getting all messages from the list.

The issue is that some mail servers have become more strict about what
mail they send and accept. Some servers cryptographically sign outgoing
messages (using "DKIM") so forgeries can be detected. Some servers
reject incoming messages if there's a signature and it doesn't match.

Many mailing lists, including this one, change some of the mail headers
-- most obviously, the subject line gets "[ClusterLabs]" added to the
front, to make list messages easy to filter. Unfortunately this breaks
DKIM signatures. Thus, if someone sends a DKIM-signed message to this
list, some recipients' servers will reject the message. After a certain
number of rejections, this list's server will automatically unsubscribe
the user.

Luckily, most servers that are configured to reject broken DKIM
signatures are also configured to accept the mail anyway if the sending
domain has proper "SPF" records (a DNS-based mechanism for preventing
address spoofing). We have just added SPF records for clusterlabs.org,
so hopefully the situation will improve for users who have been
affected.

If anyone continues to have problems after this point, please let us
know (either to this list or directly to me).
-- 
Ken Gaillot <kgaillot at redhat.com>