Gmail rejects mail from submission.tpo as spam from time to time
This is at least the second case where a mail I sent to a Gmail address bounces back and could not get delivered (I needed to fall back to using Riseup). Here is what I got (the mail address I sent to being redacted):
This is the mail system at host submit-01.torproject.org.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
<XXX@gmail.com>: host gmail-smtp-in.l.google.com[2a00:1450:4010:c02::1b]
said: 550-5.7.26 This message does not have authentication information or
fails to 550-5.7.26 pass authentication checks. To best protect our users
from spam, the 550-5.7.26 message has been blocked. Please visit 550-5.7.26
https://support.google.com/mail/answer/81126#authentication for more 550
5.7.26 information. o25-20020ac24359000000b004437b0e446asi11253489lfl.62 -
gsmtp (in reply to end of DATA command)
Reporting-MTA: dns; submit-01.torproject.org
X-Postfix-Queue-ID: A948A80095
X-Postfix-Sender: rfc822; gk@torproject.org
Arrival-Date: Tue, 1 Mar 2022 08:03:06 +0000 (UTC)
Final-Recipient: rfc822; XXX@gmail.com
Original-Recipient: rfc822;XXX@gmail.com
Action: failed
Status: 5.7.26
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.26 This message does not have authentication
information or fails to 550-5.7.26 pass authentication checks. To best
protect our users from spam, the 550-5.7.26 message has been blocked.
Please visit 550-5.7.26
https://support.google.com/mail/answer/81126#authentication for more 550
5.7.26 information. o25-20020ac24359000000b004437b0e446asi11253489lfl.62 -
gsmtp