Why I am getting bounces for Microsoft Ids (Hotmail, Live, Outlook)?

When sending emails, the inbox provider scrutinizes various details about the sender and the email itself. This includes aspects like the subject line, email content, links within the email, sending speed, IP/domain reputation, past mailing behavior, previous interactions with the user, presence in the user's contact list, and more.

If the inbox provider detects spammy content, blacklisted IPs/Servers/domains, spammy links, flagged subject lines, or excessive email sending within a short time frame, they may reject the email based on these factors.

However, not all ISPs are equally restrictive. Some, like Outlook, Hotmail, and Live IDs, are particularly stringent, making it challenging for even reputable senders to reach their users' inboxes.

In bounce messages, you may observe rejections due to IPs (not necessarily yours but others from the same network) being on the block list, leading to non-acceptance of emails.

Regarding configuration concerns like incorrect DNS or mismatched rDNS, in every email server setup, we ensure proper configuration with SPF, DKIM, DMARC, and proper rDNS settings, as these are fundamental requirements. We conduct thorough testing to ensure all encryption protocols are correctly implemented before delivering the server setup.

What could be the problem then?

Microsoft itself mentioned many reasons for this as follows on their website.

 https://sendersupport.olc.protection.outlook.com/pm/troubleshooting.aspx#errors

Microsoft bounce reasons

Should I consider changing the IPs or the server provider (moving away from OVH to another VPS provider) for this purpose?

We've chosen a select few VPS providers for our bulk mailing needs, with OVH being one of them due to its unrestricted server and IP offerings, especially for bulk mailing.

Many server providers have already restricted mailing ports like 25, 587, and 465 due to spamming concerns, leaving us with limited options for mailing servers.

OVH doesn't pose such issues, but because many users, including some spammers, use their servers/IPs for bulk mailing, Microsoft has blocked entire networks rather than specific IPs.

Even if we change the IPs or switch to another VPS provider, there's a high chance that Microsoft's servers will block those IPs or network ranges by default.

It is only the OVH that was blocked by Microsoft but they blocked all those server providers who provided their server for bulk mailings such as Digital Ocean or even Amazon AWS servers too.

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_o365admin-mso_other-mso_o365b/ndr-digitalocean-ips-blocked-by-office365-smtp/e0d97f59-83ac-450b-9f88-5d5cb83ec94e

 https://answers.microsoft.com/en-us/outlook_com/forum/all/outlookcom-is-blocking-amazon-aws/466dd363-3f85-4bb4-af3f-70cfea447ef1

https://answers.microsoft.com/en-us/outlook_com/forum/osecurity-oother/email-server-being-blocked-by-outlookcom-despite/faa11dc9-c71c-436c-8ad0-72b575ab66aa

Can I request the removal of my IPs?

There is not direct removal but you can follow these processes.

Although it will be hard (especially if you will send the non-optin mailing) to comply with all the things you can try the following thing.

1. Return Path Certification

Learn more at https://returnpath.com/solutions/email-deliverability-optimization/ip-certification/

2. Junk Email Reporting Program

Enroll at https://postmaster.live.com/snds/JMRP.aspx and typically start receiving feedback within as little as 72 hours

3. Smart Network Data Services

Learn more at https://sendersupport.olc.protection.outlook.com/snds/

Conclusion:

We don't want to disappoint or discourage you but these things are very common due to the nature of mailing that few of the ISPs will be rejected and bounce back your emails, so it will be suggested to focus on other ISPs which will still accept your emails and focus on your overall open rate.