----- Original Message ----- | From: "Rob McEwen via mailop" <[email protected]> | To: [email protected] | Sent: Thursday, August 14, 2025 2:00:24 PM | Subject: Re: [mailop] Microsoft blocks forwarding mails from "large senders" (MUST spf pass)
| ------ Original Message ------ | From "L. Mark Stone via mailop" < [ mailto:[email protected] | [email protected] | ] > || FWIW, our company focuses on Zimbra software, and in the Zimbra web client, when || you select the "Forward" action, the Zimbra web client actually crafts a brand || new email message but tarts it all up to look like a forward. Such emails then || pass SPF no problem, since the envelope sender's domain is the user doing the || "forwarding". | Mark, | This is an excellent feature overall - I wish more systems had something like | this built-in - but as I'm sure you're aware - it can greatly backfire if/when | spam slips past the filter and gets forwarded - but systems with | better/superior filtering are going to have far FEWER issues that those with | poor or average spam filtering.... because it sure seems like the recipient | email hosts (especially the large providers) - are going to assign MORE blame | for THESE types of spams that get forwarded in THIS way - than they would if it | was a "regular" forwarding. (I don't have a shred of evidence to back that up - | but that's a very very "educated guess") Hi Rob! You are of course preaching to the choir. :-) We do not allow customers to configure automated forwarding to off-domain addresses, and run a script periodically to check that no one is doing so. If caught, we tell them that we have removed the automated forwarding; suggest they configure the recipient system to fetch their Zimbra email and we are done. Once I had a user at a customer that just recreated the filter a few days later, and so we just turned of forwarding entirely for that user's account, letting their sysadmin know what we had done, and why. The sysadmin was grateful; the user had been a problem in other respects. | This doesn't mean that such a feature is bad idea - but that does make it all | the more important that such a feature only get implemented if/when email | hosting system that is doing such forwarding - has very accurate and | high-quality spam filtering. (Unless someone just wants their mail server to | suddenly have massive across-the-board deliverability issues to the large | providers.) Well, the accuracy and quality of our spam filtering is kinda up to you, isn't it? We are one of your (very satisfied and long-term) customers after all! ;-) | Also, is this a feature that is built into Zimbra? Or something you custom | implemented? | (just curious) The "Forward as new" feature is built in to Zimbra by default. Turning off forwarding entirely for selected users, domains, etc. is also built in to Zimbra. Users can also Redirect emails, but that will cause SPF fails (unless we host the recipient domain as well). Lastly, I do allow intra-Zimbra forwarding no problem. A number of customers have email-based, often semi-automated workflows, so wind up sending a lot of intra-domain emails, some portion of which are forwarded by filters. Hope that helps! Mark -- _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
