Hi, Our ESP products have been seeing the same since August 28th and I've heard others in the industry are too. It all started when atmailcloud.com took over the MX for several domains that used to MX to virginmedia.com. This mainly includes addresses for @ntlworld.com, @virginmedia.com, @blueyonder.co.uk and @virgin.net.
Delivery has been impacted since then and we also have seen the "421 Too many concurrent SMTP connections; please try again later." responses even when making 100% sure we only make one connection per IP. In the beginning we had a massive deferral issue as well, but the Atmailcloud postmaster made some changes for us. Delivery has been fine since but we do still get the concurrent message responses. So my advice is you should email their postmaster too and ask for help. Just make sure you contact the Atmailcloud postmaster. Google will give you the correct email address. Good luck! Dan ________________________________ From: Henry Thomas via mailop <[email protected]> Sent: Tuesday, October 6, 2026 10:05 To: [email protected] <[email protected]> Subject: [mailop] help - virginmedia aggressive filtering Hi, I work at a mailing list company and one of our customers has had emails bouncing for those with virginmedia email addresses. We can see on our end that they are aggressively filtering on concurrent connections and content. I wanted to ask whether a) this is a widespread problem and b) if you know of any ways to contact virgin media regarding this? I tried contacting a generic postmaster@ email but received no reply. My apologies if I have not sent this request in the correct format, it is my first time emailing mailop. Thanks, Henry
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