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Old 20 Mar 2017, 04:31 AM   #12
Intergalactic Postmaster
Join Date: May 2004
Location: Irving, Texas
Posts: 8,374
Just because you stop receiving periodic emails doesn't mean the reason is the receiving email system spam content filtering. Here are some possibilities:
  • The sending system isn't sending you the messages. You can contact the newsletter support department and ask if their systems show that emails sent to you were delivered or bounced. For some reason they may have removed you from the list.
  • The delivery address is incorrect. If it's an alias, be sure it is set up to deliver to your account. Try sending an email to that address and make sure it is immediately received.
  • The sending server is acting like a spammer during the SMTP connection process. Fastmail (and other quality email providers) performs checks to block most incoming connections from spammers. Here is a description of these checks:
  • As you can see in the link above, Fastmail uses the SpamHaus XBL to block incoming connections from known compromised sending IP's. Here is what this blocks:
    The Spamhaus Exploits Block List (XBL) is a realtime database of IP addresses of hijacked PCs infected by illegal 3rd party exploits, including open proxies (HTTP, socks, AnalogX, wingate, etc), worms/viruses with built-in spam engines, and other types of trojan-horse exploits.
  • As also noted in the link above, Fastmail also uses a few RHSBL blocking lists, which block the identity (domain name) of email servers which attempt to connect to Fastmail.
  • The link above also describes other causes for blocking connecting servers. One common reason is many people marking such advertising messages as spam. If you file a Fastmail support request with full information about the newsletter sender (such as one email containing full headers which was received somewhere), Fastmail may be able to determine why delivery is failing. They may contact the support staff at the newsletter, for example.
  • If the message contains a suspicious attachment (virus or file with certain filename extensions such as .pif, .scr, .cpl, .com or a double-extension such as .txt.exe) the message may also be blocked at the SMTP stage.
  • All of the issues I have described so far block the message from being accepted at the SMTP (server connection) stage and the newsletter service should have server records showing this rejection.
  • If the message is accepted by Fastmail incoming servers and is not a virus, the message is transferred to the sieve rules filtering system. One additional issue is DMARC, which allows the sending domain to specify using SPF which servers are allowed to send for that domain and can add DKIM digital signatures to messages. If the message was forwarded it's possible that DMARC can fail, which might cause the message to be deleted. The sender (in this case the newsletter service) has control over which sending domain and their DMARC policy, so you should not automatically forward/redirect emails if you want delivery to be guaranteed.
  • You can choose how messages are filtered in the Settings>Spam Protection and Settings>Rules screens. If you make choices which do not discard any messages, then the newsletter should be in your account if it was accepted by the Fastmail incoming server. Of course, you might be automatically be filing certain incoming messages into a particular folder using rules or plus+addressing, so you might want to use the search feature to find the message. By default all folders are searched except Spam and Trash. You can search in either of those folders by opening the folder before performing the search.
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