Desde 13 de Janeiro de 2023 que, sensivelmente a cada 2 meses, os servidores de correio da 3GNTW são bloqueados pela Microsoft sem motivo aparente, impossibilitando a entrega de email para destinatários dos seguintes serviços:

*@hotmail.com
*@live.com
*@msn.com
*@outlook.com

Sempre que isso acontece a 3GNTW faz 2 coisas:

1. Altera o endereço IP de saída das mensagens, contornando a limitação, e tentando minimizar o impacto para os seus clientes;
2. Abre um pedido de suporte junto da Microsoft, solicitando o levantamento do bloqueio e um pedido de explicações sobre porque é que ele acontece a cada 2 meses.

Passadas algumas horas a Microsoft responde que "aplicou medidas de mitigação", levanta o bloqueio, mas recusa-se a prestar mais explicações, apesar da nossa insistência. Um exemplo dessas trocas de mensagens:

3GNTW:

550 5.7.1 Unfortunately, messages from [193.227.239.7] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors.

As you can see, our 193.227.239.7 IP address is on your block list.

However, our email server with the IP address 193.227.239.7 is currently not listed in any public RBL. We have "neutral" reputation on TALOS reputation center. We have no problem sending to any other domains, including Gmail accounts, but we are not able to send to hotmail.com, live.com, msn.com and outlook.com recipients.

This block happens about every 2 months, and Microsoft never provides any clear explanation why our email server is blocked, and why are tens of thousands of our users being prevented to send email to hotmail.com, live.com, and outlook.com recipients.

We host mailing lists, (which the recipients explicitly subscribed, no SPAM is allowed). We also work as mail relay for web applications which need to programmatically send email, (ex. invoices generated and sent at night, school meeting request for parents, students and teachers, etc...). As such we have "sudden changes in email sending volume", but we have no reports of abuse.

We expect from you some indication of problem (ex. Message-ID, dates, from/to addresses) that allow us to discover and confirm some kind of problem we are not aware of.

We already joined the Smart Network Data Services program (SNDS), all of our IP addresses have "normal status" there. We already joined the Junk Mail Reporting Program (JMRP), we received no junk email reports there.

PLEASE EXPLAIN WHY OUR IP ADDRESS IS BEING BLOCKED EVERY 2 MONTHS.

We have no knowledge of any SPAM or malware outburst, so can you please explain why can't we send email to hotmail.com, live.com, msn.com and outlook.com recipients ?

We cannot fix any problems we can't identify.

Microsoft:

We have implemented mitigation for your IP 193.227.239.7 and this process may take 24 - 48 hours to replicate completely throughout our system.

3GNTW:

Thank you for removing our 193.227.239.7 IP address from your blacklist.

However, this is the THIRD time Microsoft blocks our IP address and "applies mitigation" after us complaining, with no justification for the blocking. No "Date", "From", "To", "Subject", "Message-ID", absolutely no information needed to debug any problem on our side.

We need to provide our clients with an explanation. We need to know why our IP address was blocked. Please explain.

Microsoft:

I do apologize, but I am unable to provide any details about this situation since we do not have the liberty to discuss the nature of the block. Also your IP 193.227.239.7 has already been mitigated. At this point, I would suggest that you review and comply with Outlook.com’s technical standards. This information can be found at https://postmaster.live.com/pm/postmaster.aspx.

We regret that we are unable to provide any additional information or assistance at this time.

Pedimos desculpa aos nossos clientes por este incómodo periódico, mas nada mais podemos fazer para eliminar estes bloqueios a título definitivo. Eles originam na Microsoft, que não presta explicações sobre o seu motivo.

Agradecemos que nos informem sempre que depararem com problemas na entrega de email para destinatários *@hotmail.com, *@live.com, *@msn.com ou *@outlook.com, para contornarmos eventuais bloqueios da Microsoft o mais rapidamente possível.

Mantemos um registo destas ocorrências aqui:

2023/01/13: ticket #SRX1545238153ID
2023/05/15: ticket #7017678109
2023/07/17: ticket #7021141881
2023/09/20: ticket #7024329213
2023/11/21: ticket #7027981820
2024/01/21: ticket #7033160233
2024/03/26: ticket #7038015179
2024/05/27: ticket #7042342597
2024/07/30: ticket #7047480860
2024/09/29: ticket #7052939955