For Belgian ISP Belgacom (Proximus, Skynet) we've seen a typical rate for established senders of max 2 smtp connections simultaneously and 60 connects per minute. I would advise definitely to stay bellow that while warming up.
Last I've known they were using Cisco border protection so might be worth checking your reputation on Thalos Intelligence. Apart from that , get in touch with their postmaster team and explain the situation, they are normally happy to assist Bram Van Daele Founder E: [email protected] M: +32 (0)478 36 08 18 A: Teneo BV, Legendaledreef 58 - 8020 Oostkamp, BELGIUM - VAT BE 0809.520.032 esp.teneo.be -----Original Message----- From: mailop <[email protected]> On Behalf Of Renaud Allard via mailop Sent: Thursday, 21 May 2026 12:20 To: [email protected] Subject: Re: [mailop] Transactional Email to Proximus' scarlet.be - How to provide proof of High Volume Sender On 5/21/26 12:00 PM, SecOps, Dev via mailop wrote: > Yes I understand all that. I'm just looking for a bit of clarity on > the triggers, let's say they have limits, no more than 10% increase in > new connections? 5? > I remember that I had a specific rule for @skynet.be, but it's not only for @skynet.be but all mails hosted by proximus. In exim, I had to put queue_smtp_domains = skynet.be It might have been changed, bu that's how it used to work. > Knowing those, I would be able then to tune my relay to queue messages > accordingly. > > On Thu, May 21, 2026 at 11:45 AM Laura Atkins <[email protected] > <mailto:[email protected]>> wrote: > > Often connection limits are reputation based - known good senders > get higher connection allowances than unknown or known-poor senders. > This might be a good place to look at the number of connections > you’re making from your dedicated IP while getting that message. I’d > also look at the connections pooled over recent time periods. It’s > likely this is just part of the warmup process and you’re going to > have to finesse things for a few weeks during warmup. > > laura > >> On 21 May 2026, at 10:27, SecOps, Dev via mailop >> <[email protected] <mailto:[email protected]>> wrote: >> >> We're in the process of moving out of AWS SES Shared pool, into a >> dedicated IP, and we're trying to build up reputation slowly but >> we're still hitting some sporadic rate-limiting responses like below: >> >> 421 #4.4.5 Too many connections from your host. >> >> >> It would be great to know exactly what they expect so that we can >> comply with the increase in volume. >> >> On Thu, May 21, 2026 at 11:00 AM Bram Van Daele (Teneo BV) >> <[email protected] <mailto:[email protected]>> wrote: >> >> What specific SMTP responses are you getting from their border ? >> Skynet is particularly picky when it comes to simultaneous >> SMTP connections .____ >> >> __ __ >> >> *From:*mailop <[email protected] <mailto:mailop- >> [email protected]>> *On Behalf Of *SecOps, Dev via mailop >> *Sent:* Thursday, 21 May 2026 10:37 >> *To:* [email protected] <mailto:[email protected]> >> *Subject:* Re: [mailop] Transactional Email to Proximus' >> scarlet.be <http://scarlet.be/> - How to provide proof of High >> Volume Sender____ >> >> __ __ >> >> I'm sorry, I meant skynet.be <http://skynet.be/> ____ >> >> __ __ >> >> On Thu, May 21, 2026 at 9:57 AM SecOps, Dev <[email protected] >> <mailto:[email protected]>> wrote:____ >> >> Hello List,____ >> >> __ __ >> >> This is my first email to the list. I'm wondering there's >> if anyone here from Proximus managing the rate-limiting >> queues of the /scarlet.be <http://scarlet.be/>/ domain >> that could point me in the right direction. ____ >> >> __ __ >> >> I can reach off-list from my professional *.be* TLD domain >> if that's a blocker. ____ >> >> __ __ >> >> Best Regards,____ >> >> __ __ >> >> TIA,____ >> >> __ __ >> >> [email protected] <mailto:[email protected]>____ >> >> -----BEGIN PGP PUBLIC KEY BLOCK----- >> >> mDMEag66CBYJKwYBBAHaRw8BAQdAMNVdlzezcwCNwLaa9fsc3Jh+X7rCDOyHphgD >> FICOMhK0MVNSRURldiBTZWNPcHMgKG1haWxpbmctbGlzdHMpIDxkZXZvcHNAZGl6 >> b3JnLm5ldD6IkwQTFgoAOxYhBPpHG9wc7t+sdIXWcXraqS6BSNNEBQJqDroIAhsD >> BQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJEHraqS6BSNNEjRcBAPbEMYmZ >> 3gJpjk+3Roo1Ck5qjLFolQds3+0zQMXQgQ3QAQCO6AeBHPnKqvz4MArJfZODWras >> xft87BUm9wF+Q3OWArg4BGoOuggSCisGAQQBl1UBBQEBB0DI9NAzy+4PT28vFrsf >> wfDdujqMpL0yEmRcis3nUry6FQMBCAeIeAQYFgoAIBYhBPpHG9wc7t+sdIXWcXra >> qS6BSNNEBQJqDroIAhsMAAoJEHraqS6BSNNEQb4A/1mO9Qmu1mBzyI5OmPE0RIkP >> aKt/ >> aG5EsWoLXTML3YyqAQDdAC0kzhAvN9jDSqCnxU8E6O9O7NXcaaHXMtbffyQu >> BQ== >> =phdp >> -----END PGP PUBLIC KEY BLOCK-----____ >> >> _______________________________________________ >> mailop mailing list >> [email protected] <mailto:[email protected]> >> https://list.mailop.org/listinfo/mailop <https://list.mailop.org/ >> listinfo/mailop> > > — > Demystifying “It Depends...” since 2001 > > Laura Atkins > Word to the Wise > [email protected] <mailto:[email protected]> > > Delivery hints and commentary: http://www.wordtothewise.com/blog > <http://www.wordtothewise.com/blog> > > > > > > > > _______________________________________________ > mailop mailing list > [email protected] > https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
