They might have legacy accounts where port 25 is unblocked. I think Infusionsoft/Keap had their IPs hosted at GCP at one point and they had the port 25 block lifted to send with them.
Thanks, Alex -- Alexander Burch ActiveCampaign / Senior Deliverability Engineer [email protected] 1 North Dearborn St Suite 500, Chicago IL, 60602 <https://www.facebook.com/activecampaign> <http://www.twitter.com/activecampaign> <https://www.linkedin.com/company/activecampaign-inc-> <https://plus.google.com/107063868317743606466> <https://www.activecampaign.com/sig/?u=aburch&c=1> On Thu, Sep 4, 2025 at 9:12 AM Scott Q. via mailop <[email protected]> wrote: > I get that, but the question is more whether GCP blocks outbound port 25 > or not. Their docs say they are blocking it: > https://cloud.google.com/compute/docs/tutorials/sending-mail > <https://cloud.google.com/compute/docs/tutorials/sending-mail> > yet we see evidence to the contrary. Surely it's a configuration mistake > somewhere (?). Maybe > someone > > > > > > > > > > > > > > > > > > > > > > > > > > > <https://login-usb.mimecast.com/u/login/?gta=apps&link=cybergraph-report/eyJhbGciOiJSU0EtT0FFUC0yNTYiLCJlbmMiOiJBMjU2R0NNIn0.L4f2Kd1MQgyXiAST4gOoAepBm089vlIho54qPBEzii9WazwOH0VrM1IuRW7uuLYziNN84J-PwRFx3jVRWaz2JXjERNUmyreltVqsHfKldUFCf4RqTy7JQpFKdM_W7fwe5JBaixXNOceWDSjH6rHKlKiRA7AKhOGNFK42-N-kNKMzILxNLGglD-iXf_AgUbJ9dqWeCKA2p8LOfD4sT6yQfzP21D27j180-JQLyCU7wKAaebw50Am7n9HNk6IyHHI4VLvoTs28rkud84U6DwhvQN6GRFBVnxQcfa0bDPiXEd-FoUa50EdM6a0pOavuKKLtbawaTy-NCz56SYYV2U6eyQ.wKJ7VsU8Z-vXP9Zn.hNyUHb5Oral1w_auu3ulPx7ai6edGS5N_AITTm44cvQOJNZylJ9dyuIkgJwCSIFBz3IfOD5yrlsMBD4ZNtOdfWZemI63XOK8m8mB-Lozy3rkFrLFtLt_vZTdlsrbZwi9DANADCmYu9V-NwQ4_dYeXM43OJw19jO86OTQX1tOj-F0sMq1M4bjUrg_bi9NvqgCslIx-V-uCd0nJbW4Swk_WCam9nOq5ZR3JVZYBSut4CeqNMDcn5gDSZHQXzLhhNGScrK3XqTp32_6jLc5laW6JSahAn_m6ww0j0L7t47YfQNQteFlXrfigL0TrMeEdoLmJiwVbH561tVXI_XFZHQstJDgPjYYoK_636uvWATHLZf8V7l3eJMjVbpckRU5GPUPfkcLclplPbRo0kPkUsZxgMO71VZC5FjZy9H-WJgfoEw03oZf588fmuPenLUe6LHDsgRlHVXsqDHCxBuP.isxv-P5VHWFJEuPebwKWRA> > CGBANNERINDICATOR > > I get that, but the question is more whether GCP blocks outbound port 25 > or not. > > Their docs say they are blocking it: > https://cloud.google.com/compute/docs/tutorials/sending-mail > <https://cloud.google.com/compute/docs/tutorials/sending-mail> > > yet we see evidence to the contrary. Surely it's a configuration mistake > somewhere (?). > > Maybe someone from Google can shed some light on this. > > Thanks! > > On Thursday, 04/09/2025 at 11:25 Michael Peddemors via mailop wrote: > > Careful.. the list admins don't like us using this list to complain > about spam, but yeah.. > > Anything with a PTR of 1.132.64.34.bc.googleusercontent.com. is suspect, > and should be rejected (port 25) ... > > Standard ruleset for a couple of years.. but even more important, is the > number of IPs in those ranges used in email hacking, and BEC Compromise > attacks. > > You might even like to block attempts to other ports by default, and > create a 'permitted' acl for IPs in those ranges for legitimate use. > > On 2025-09-04 07:55, Scott Q. via mailop wrote: > > Anyone else seeing an uptick lately of Spam e-mails originating from > > these ranges ? > > > > 34.64.132.0/22 > <http://34.64.132.0/22> > > 35.240.0.0/13 > <http://35.240.0.0/13> > > > > Mostly e-mails with: Content-Type: text/plain; charset="iso-2022-jp" > > > > What's interesting is that GCP has outbound port 25 blocked by default > > yet these hosts are able to do direct-to-mx deliveries. > > > > If anyone from Google is reading this - can you have a look ? > > > > Thanks! > > Scott > > > > > > _______________________________________________ > > mailop mailing list > > [email protected] > > https://list.mailop.org/listinfo/mailop > <https://list.mailop.org/listinfo/mailop> > > > -- > "Catch the Magic of Linux..." > ------------------------------------------------------------------------ > Michael Peddemors, President/CEO LinuxMagic Inc. > Visit us at http://www.linuxmagic.com > <http://www.linuxmagic.com> > @linuxmagic > A Wizard IT Company - For More Info http://www.wizard.ca > <http://www.wizard.ca> > "LinuxMagic" a Reg. TradeMark of Wizard Tower TechnoServices Ltd. > ------------------------------------------------------------------------ > 604-682-0300 Beautiful British Columbia, Canada > > _______________________________________________ > mailop mailing list > [email protected] > https://list.mailop.org/listinfo/mailop > <https://list.mailop.org/listinfo/mailop> > > _______________________________________________ > mailop mailing list > [email protected] > > https://list.mailop.org/listinfo/mailop > >
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