Mails sent to mail.protection.outlook.com are not being received

Question

For few days we have been receiving complaints from many of our subscribed clients that they are not getting daily alert mails. We checked in our logs that the mails are accepted by the servers (MX record: example.com.mail.protection.outlook.com), but all clients subscribed to this service are not getting our mails in their inbox. Mails are accepted without any fault by the client mail server.

Following is the log from our sendmail server. Note: we have valid SPF records. Also, our mail server is not blacklisted anywhere. Mail contains HTML embedded info about our services for which the client is subscribed.

to=<[email protected]>, delay=00:00:08, xdelay=00:00:08, mailer=esmtp, pri=206583, relay=xxxxx-co-za.mail.p...ction.outlook.com. [xxx.xxx.154.23], dsn=2.0.0, stat=Sent (<VPOP31.4.0e.20140910113951.917.f85.2.34364a7d@CMS1> [InternalId=58007828300753, Hostname=xxxxxxx.eurprd03.prod.outlook.com] Queued mail for delivery)

What should we do to work around this problem?

Solution

We had a very similar problem a while ago. The reason, in our case, was threefold:

1. Microsoft rely on their own spam blacklist, which is not included in the normal blacklist checks, such as MX Toolbox.
2. Microsoft do not use standard methods of rejecting spam mail: instead, they accept it and then dump it into a black hole, so normal diagnostics will not work properly.
3. Microsoft have a get off our spam blocklist form, but if you open it in Firefox you get a Page Not Found error (it does work in Chromium).

Fill in that form, and follow all instructions. At the end, you have an option to sign up to alerts from their own spam blacklist.

Comments

[vivek.teli]

ok Trig .. i will try to fill up the same .. hope it will solve the issue because most of our clients moved on to office 365 outlook and all of them facing the same issue which is now creating bad impression of our mailing system.. Thanks for reply .. will update the same.

[DGK]

Is there a solution to this in 2018? Site does not work on chromium any more

[TRiG]

I really don't know, @Laurens. I haven't dealt with email in a while.

[DGK]

Np, in any case your information is correct. We contacted microsoft and we were helped reasonably quickly