Tuesday, September 27, 2016

DreamHost’s New Mail Filtering

I’ve long recommended DreamHost as a mail provider because they allowed full user control. Alas, that is no longer the case. It started with the creation of Promotion and Social mailboxes, which could not be turned off. There was an outcry, so the feature was temporarily removed until a setting could be added.

However, a new spam filter was also introduced, and unlike DreamHost’s previous offering, there is no way to disable it. This is an issue for several reasons. First, I already use a more accurate spam filter and some Mail rules to organize messages just the way I want. I don’t want the spam sprayed across different account mailboxes. Messages in server mailboxes are ineligible for processing with Mail rules, add IMAP syncing overhead, and can be difficult to deal with in Mail because it doesn’t always cache messages that did not arrive in the inbox.

Second, the new filter makes lots of mistakes. I had more than 1,000 false positives (good messages in the Spam mailbox) in the first few days. And this was despite creating whitelist rules that matched the vast majority of those messages, but which were for some reason ignored. The messages were almost all from the same domain, which I blanket whitelisted at the highest priority, so there’s no reason this shouldn’t have worked. The whitelist rules are also limited, so even if they worked you could not effectively disable the filter by creating a rule that whitelisted everything (or even everything from a particular mailing list).

Lastly, some of my accounts are monitored by FogBugz. I don’t check them from regular mail clients, so there is no opportunity to review the contents of the Spam mailboxes. FogBugz only checks for new messages in the inbox, so any falsely caught good messages will be silently ignored. I’ve temporarily worked around this by creating DreamHost forwarders to forward those addresses to a FastMail account. DreamHost does not apply its spam filter to forwarded messages, and FastMail’s own filter can be turned off. So this setup allows FogBugz to see all the messages.

What about the other accounts? It’s actually quite common for mail providers to have server junk filters that can’t be disabled. This is usually not a problem so long as they put the messages in the Spam mailbox rather than deleting them sight-unseen. There are a variety of ways to deal with this, whether or not you are using a client-side filter such as SpamSieve.

Update (2016-10-18): The DreamHost whitelist rules are still not working, and the support people have not been able to explain to me why.

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