Resolved Strange Email issue

[JuanCar]

I've found an strange issue with email delivery.
I have a gmail account configured to read and send email using my outlook client in my computer. So I can send and read mails via webmail or via my mail client.
I have my mail server runnin qmail, with antivirus, antispam and so.
The problem:
1.
If I send an email using my outlook client from my gmail account to an email in my domain, I don't recevie the mail. And If I look in my gmail account using webmail I see the email as sent, and there is no error from my server.

2.
If I send an email using my gmail account using the webmail (not outlook) to an email in my domain, I recevie the mail witout any problem.

from [email protected] to [email protected] (using Outllook) NOT RECEIVED
from [email protected] to [email protected] (using webmail) RECEIVED

I can't understand the reason of this behaviour. I suppose there is a problem in config of my mail server.

I can't see anything in maillog.
Anyone have an explanation or a fix?
Thanks

 

[Bitpalast]

1) Please send a test mail from your Gmail Outlook client to an account where you can receive that mail.
2) Examine the headers (source code) of the received mail and look specifically for the first "Received: from" hop that the mail takes, like
Received: from DB5EUR03FT055.eop-EUR03.prod.protection.outlook.com
(2a01:111:f400:7e0a::206) by DB6P191CA0010.outlook.office365.com
(2603:10a6:6:28::20) with Microsoft SMTP Server (version=TLS1_2,
cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.20.1122.16 via Frontend
Transport; Fri, 7 Sep 2018 03:15:36 +0000
--> from where exactly is the mail received? Is it received from a Gmail IP address or from another non-Gmail IP?

If the mail is received from a Gmail IP, the Gmail SMTP server that is more or less accidentally picked when sending the mail through your Outlook is on a blacklist, so that the receiving system blocks the incoming mail before it is processed by any other steps.

But more likely the first hop is not a Gmail IP, but an IP from either a local SMTP gateway or an SMTP server of your internet access provider. Such servers often are blacklisted, because millions of others use them, too.

 

[JuanCar]

Thank's, you are right it was a problem with black lists. When I disabled black lists protection in my mail config the problem became solved.
I couldn't imagine that a Gmail server could be on a black list!!.