For the last several weeks I have been tracking slow email from several sources. When it is easiest to see is when an outside source will send an email to two or more of our employees at the same time. One email copy to one person will show up right away and the other might be several hours later. Often we have had one employee reply all to the message and the other employee will notice they didn’t get that part of the email thread as the Reply All is received before the original.
Looking at the logs on our end show nothing. No attempt for that message at the time it was originally sent. Investigating email headers when it finally arrives reveals the message’s path and it sat for a long time at the senders’ last email server in the list. These servers usually are some third party relay and have included google.com, outlook.com, iphmx.com, cudaops.com, mimecast.com and probably more that I haven’t found yet. If you work with one of these relays and can shed light on the delay I would love to know how to get it fixed. If you have examples of this you have been tracking in the last month and a half or so I would like to hear about what you have discovered. I have asked several of the other sending organizations for email logs and error messages but have not had any usable response. I did look at the possibility of incoming greylisting. Our Barracuda does not support it and it is not enabled. Also, if this was the issue the Barracuda should make some log entry that the email was delayed. We created a support ticket with Barracuda and came up with no log entries prior to when it was received. It was like it sat in a queue for many hours. I also took the time to ensure these senders were in our whitelist and that did not help either. Because it is intermittent and eventually arrives I think I can rule out most routing issues and I did double check DNS but see no changes there. Yesterday: One of our customers sent us an email asking us to cancel a delivery about 8am yesterday. We received the email 19 hours later and they got the product they didn't need about 3 hours after the email left the client's system. The customer uses Gmail to provide backend email services. See attached screenshot of header analysis. Thanks in advance, Job
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