Score:0

Box email - subset of domains have stopped working

us flag

I am hosting a Box instance on a Bytemark server. I host twenty or so email domains there (for my business and family) and have been for five plus years.

Yesterday, two of the domains have been receiving email very sporadically. Test emails sent from some (external) servers have never arrived. Some have arrived six hours later.

Other domains served seem to be absolutely fine. For example, I send an email to one of the broken domains and cc one of the working ones. The working one immediately arrives; the other takes 6 hours. I've repeated this test multiple times.

I've looked at the Box admin status page, and nothing seems amiss; nor can I see an obvious pattern between the domains that are failing.

I'm at a complete loss!

UPDATE

Many emails are starting to come through, but with a 12-24 hour delay.

codlord avatar
mp flag
I would first check if any of your sending/receiving domains/IPs have been blacklisted. One such tool is https://mxtoolbox.com/blacklists.aspx I don't know if there is much you can do about it but it might explain some issues if you find any blacklisted.
Omroth avatar
us flag
Cheers. Only one blacklist - UCEPROTECTL3 - I don't know if that's a big one.
vidarlo avatar
ar flag
What does the headers show? They may indicate where the mail was held up. What does incoming logs show? Was the message rejected by the MX?
Omroth avatar
us flag
X-Greylist: delayed 43271 seconds by postgrey-1.35 at box.mydomain.com So that's a big red flag!
Paul avatar
cn flag
This sounds like `postgrey` doing its job. The length of time for the sending server to re-send is based on its own configuration. If these are very large senders, they may have more than one sending server and not configured to use the same server for a given domain.
Omroth avatar
us flag
This is the other part which looks relevant - where can I find why (if) it was originally refused? Received: from AM7PR09MB3799.eurprd09.prod.outlook.com (2603:10a6:20b:de::22) by DB7PR09MB2378.eurprd09.prod.outlook.com (2603:10a6:10:4a::12) with Microsoft SMTP Server (version=TLS1_2, cipher=blah) id 15.20.5061.24; Sat, 12 Mar 2022 15:45:51 +0000 Received: from AM7PR09MB3799.eurprd09.prod.outlook.com ([fe80::d72:e879:3b8:e625]) by AM7PR09MB3799.eurprd09.prod.outlook.com ([fe80::d72:e879:3b8:e625%5]) with mapi id 15.20.5061.026; Sat, 12 Mar 2022 15:45:51 +0000
Paul avatar
cn flag
Use `grep messageidstring /var/log/mail.log` to find all of the transactions with the message.
Omroth avatar
us flag
I'm finding it hard to divine the message id string from the headers
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