We are closing this issue, although we have not found a cause. As far as we can tell, everything related to authentication on the server is working. Research on similar occurrences also shows the problem apparently resolving itself after a short time, and also points to a number of possible causes, including faulty operating system and software updates on client machines. However, in this case we saw the problem on different operating systems (Windows, Mac and Android) and different email programs. We also suspected anti-virus software, but again we heard of problems on computers running different anti-virus software.
Oddly, we could not reproduce the problem on any machines in our office, and so we had no primary references on which we could do research.
About the only commonality we could find — other than the server itself, of course — is that we believe all of the reporting clients are on VSATs. However, even that doesn’t fully explain the problem as if, for some reason, VSATs were the issue we should theoretically have seen the same problem on other servers. That said, the problem reported to us was only with downloading email, and the other mail server on which the bulk of our clients are hosted uses slightly different SSL technology; additionally our default instructions for that server do not mention using SSL. We saw a similar issue with VSAT connections several years ago, so if this is related it’s not unprecedented.
Another possibility that can’t be ruled out is network issues that may have interfered with encryption on the connection. Given the number of reports, such an issue (if it existed) would likely have been closer to the server than the client. If this issue reoccurs we will contact our upstream providers to see what they have to say.
While it is unsatisfactory to close an issue without having a smoking gun to identify it, we are going to do so at this time. If you do see this issue again, please contact support and we will again look at the issue.
Thank-you for your patience while we looked at this issue.