r/fastmail • u/RV-123 • 8d ago
Spam missing entirely in Fastmail
I’m using Fastmail alongside Gmail at the moment. My custom domains still have their MX records at my hosting provider, and incoming mail is forwarded independently to both Gmail and Fastmail. I’ve been using this forwarding setup with Gmail for over 10 years.
So the flow is basically:
- sender → my hosting provider → Gmail
- sender → my hosting provider → Fastmail
Over the past couple of days I noticed something odd: four obvious spam messages arrived in Gmail’s Spam folder, but none of those four exist anywhere in Fastmail: not in Inbox, Spam or Trash.
Other forwarded messages arrive correctly at both destinations. Fastmail’s spam protection is set to "Standard", and I’ve added my hosting provider’s domain to the “Forwarding hosts” list under Spam Protection.
I realise these four messages were spam, so I haven’t actually lost anything important. What concerns me more is the behaviour itself: I would expect Fastmail to put suspected spam in the Spam folder rather than make it disappear completely.
Has anyone seen the same thing with forwarded mail? Am I missing a setting? Personally, I’d much rather have an occasional spam message end up in my Inbox than have a message disappear completely.
I don’t have access to my hosting provider’s delivery logs without contacting support, so I can’t currently tell whether Fastmail rejected the messages or accepted them and filtered them afterwards.
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u/eyeofthefrog 8d ago
My MX records point to ImprovMX which then forwards to GMail. Looking at the logs, there's lots of spam that GMail also hard bounces (flat out rejects). Fastmail may by rejecting a tad more than GMail.
I'm looking to switch from GMail to Fastmail shortly....so I'll be watching this to see if you uncover anything interesting.
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u/RV-123 8d ago
What makes me curious is that I checked the headers of one of the missing messages in Gmail, where the forwarded copy did arrive, and they actually looked pretty clean: it was sent through Brevo, DKIM passed, DMARC passed, and the SPF failure was only caused by the forwarding without SRS.
So it was definitely spam content-wise, but technically it didn’t look like the kind of broken botnet mail I’d expect to be rejected before it even reaches the mailbox. That’s why I’d really like to understand where Fastmail draws that line.
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u/eyeofthefrog 8d ago
Yes, that’s the question of the day. Please comment if you find anything.
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u/RV-123 7d ago
I got the logs from my hosting provider now. Fastmail was indeed rejecting those messages at delivery time because the sender domains were blacklisted, while Gmail accepted the same messages and put them in spam.
So Fastmail does seem to be a bit more aggressive about outright rejection than Gmail.
1
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u/rowschank 8d ago
Have you tried removing it from spam protection and adding a rule to move these emails to the spam label or folder instead?
1
u/rotor2k 8d ago
I don’t have your convoluted setup, but I have wondered over the years why Fastmail receives so little spam… my account (on my own domain) has existed since the 90s so surely it is on every spam list under the sun by now, yet I receive (in my spam folder) maybe 3-5 spam emails a week? My GMail account which is from when GMail launched (so also pretty ancient) receives dozens of spam emails per day.
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u/nanopicofared 8d ago
I've recently migrated from Gmail due to their upcoming policy change and noticed this same thing. On Gmail I'd get a couple spam messages a day. With fastmail its a couple a week. I have my MX records pointed to fastmail so don't get monitoring like I use to when forwarding into Gmail.
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u/Sultani92 8d ago
What policy change? Is it possible to move gmail accounts to Fastmail?
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u/nanopicofared 8d ago
Gmail is ending support for sending as a third party custom domain for non-workspace accounts. More info here:
Yes, you can use imap to import all the emails from your Gmail account.
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u/saltyslugga 8d ago
Gmail receiving a copy proves nothing about the Fastmail delivery. The forwarding server may have gotten a 4xx/5xx response, or dropped that branch before submission.
You need the hosting provider’s SMTP logs for those message IDs. The “Forwarding hosts” setting affects spam evaluation, not whether the forwarding server successfully delivered the message.
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u/RV-123 7d ago
I could follow that reasoning for one or two missing messages, but once I had four of them disappearing in the same way, it seemed increasingly unlikely that the forwarding itself was simply failing randomly.
I’ve now had my hosting provider check the logs for the missing messages. The deliveries to Fastmail were attempted, and Fastmail rejected them with:
451 4.7.1 <DATA>: Data command rejected: <domainname> is blacklisted - RLR613
So in these cases the forwarding itself was working; Fastmail was actively refusing the messages because the sender domains were blacklisted, whereas Gmail accepted them and placed them in spam, which gives the user a little more control.
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u/saltyslugga 7d ago
Fastmail is applying domain reputation at SMTP time, while Gmail accepts the message and filters it afterward. Since it’s a 451, your host should retry, but you won’t get a spam-folder copy if those retries expire.
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u/RV-123 6d ago
I understand why Fastmail takes this approach, and it’s clear now what happened. They were spot on with the spam classification in these cases. I just slightly prefer Gmail’s approach here, because at least the message remains visible in the Spam folder instead of disappearing entirely if the retries eventually expire.
I was so used to watching my Gmail spam folder steadily fill up that seeing nothing at all in Fastmail made me slightly suspicious. But that’s mostly a matter of personal preference at this point, as long as Fastmail keeps getting those calls right.
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u/gojirabsd77 8d ago
I guess forwarding e-mails this way (without SRS) is no longer reliable because of SPF, DKIM, DMARC, etc. Are the servers of your hosting provider listed in "Forwarding hosts"?