Problem for sending email from Roundcube and Horde

Hello everyone,

I have problem for sending email from webmail Roundcube and Horde

When I send an email with several recipients (approximately 12) and attach some files of approximately 12 megabytes in total with extensions .xlsx, .pdf and others, it says that the email I get is sent but later I receive a response with the following error.

Code:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  email-1@hotmail.com
    host hotmail-com.olc.protection.outlook.com [104.47.41.33]
    SMTP error from remote mail server after end of data:
    550 Action not taken
  email-2@gmail.com
    host gmail-smtp-in.l.google.com [74.125.142.26]
    SMTP error from remote mail server after end of data:
    550 Action not taken
Reporting-MTA: dns; my.server.net

Action: failed
Final-Recipient: rfc822;email-2@gmail.com
Status: 5.0.0
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550 Action not taken

Action: failed
Final-Recipient: rfc822;email-1@hotmail.com
Status: 5.0.0
Remote-MTA: dns; hotmail-com.olc.protection.outlook.com
Diagnostic-Code: smtp; 550 Action not taken
Return-path: <my-email@mydomain.com>
Received: from [::1] (port=57862 helo=my.server.net)
    by my.server.net with esmtpa (Exim 4.91)
    (envelope-from <my-email@mydomain.com>)
    id 1gtlM6-0003q2-IC; Wed, 13 Feb 2019 00:37:03 -0300
MIME-Version: 1.0
Content-Type: multipart/mixed;
 boundary="=_0aa43efcd0af640c6cfe9b0927c5f694"
Date: Wed, 13 Feb 2019 00:37:02 -0300
From: my-email@mydomain.com
To: email-2@gmail.com
Subject: My Subject for this email
Message-ID: <9d8d1a33787bb3f557fc3d292c61042e@mydomain.com>
X-Sender: my-email@mydomain.com
User-Agent: Roundcube Webmail/1.3.6
X-Exim-DSN-Information: Due to administrative limits only headers are returned

And in tail -f /var/log/exim_mainlog I have the following log

Code:

2019-02-13 00:37:02 SMTP connection from [::1]:57862 (TCP/IP connection count = 1)
2019-02-13 00:37:03 1gtlM6-0003q2-IC <= my-email@mydomain.com H=(my.server.net) [::1]:57862 P=esmtpa A=dovecot_login:my-email@mydomain.com S=10534706 id=9d8d1a33787bb3f557fc3d292c61042e@mydomain.com T="My Subject for this email" for email-1@hotmail.com email-2@hotmail.com email-3@gmail.com email-4@other-domain.com
2019-02-13 00:37:03 SMTP connection from (my.server.net) [::1]:57862 closed by QUIT
2019-02-13 00:37:03 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1gtlM6-0003q2-IC
2019-02-13 00:37:03 1gtlM6-0003q2-IC Sender identification U=mi_cpanel_user D=mydomain.com S=my-email@mydomain.com
2019-02-13 00:37:03 1gtlM6-0003q2-IC SMTP connection outbound 1550029023 1gtlM6-0003q2-IC mydomain.com email-1@hotmail.com
2019-02-13 00:37:03 1gtlM6-0003q2-IC Sender identification U=mi_cpanel_user D=mydomain.com S=my-email@mydomain.com
2019-02-13 00:37:03 1gtlM6-0003q2-IC SMTP connection outbound 1550029023 1gtlM6-0003q2-IC mydomain.com email-1@hotmail.com
2019-02-13 00:37:06 1gtlM6-0003q2-IC ** email-1@gmail.com R=dkim_lookuphost T=dkim_remote_smtp H=gmail-smtp-in.l.google.com [74.125.142.26]: SMTP error from remote mail server after end of data: 550 Action not taken
2019-02-13 00:37:07 1gtlM6-0003q2-IC ** email-2@hotmail.com R=dkim_lookuphost T=dkim_remote_smtp H=hotmail-com.olc.protection.outlook.com [104.47.41.33]: SMTP error from remote mail server after end of data: 550 Action not taken
2019-02-13 00:37:07 cwd=/var/spool/exim 7 args: /usr/sbin/exim -t -oem -oi -f <> -E1gtlM6-0003q2-IC
2019-02-13 00:37:08 1gtlMB-0003qN-TH <= <> R=1gtlM6-0003q2-IC U=mailnull P=local S=2458 T="Mail delivery failed: returning message to sender" for my-email@mydomain.com
2019-02-13 00:37:08 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1gtlMB-0003qN-TH
2019-02-13 00:37:08 1gtlM6-0003q2-IC Completed
2019-02-13 00:37:08 1gtlMB-0003qN-TH => my-email <my-email@mydomain.com> R=virtual_user T=dovecot_virtual_delivery C="250 2.0.0 <my-email@mydomain.com> QMHTAuSQY1ywOQAA43mkzA Saved"
2019-02-13 00:37:08 1gtlMB-0003qN-TH Completed

This only happens when I send attachments to several recipients.
I have verified that my IP is not in the SPAM list
Use the MX Lookup Tool - Check your DNS MX Records online - MxToolbox tools to verify the reverse DNS and the status of the email server configuration.

I would appreciate if you have any ideas about the possible solution of the problem I am having, several days ago I am already trying to solve and I do not find a solution.

 

Hello @cPanelLauren

Thanks for your reply


Actually I put these two emails as an example, but it happens in two situations;
- When it is sent to several recipients, it is usually sent to more than 5 email addresses.
- And also with the adjutts be .xlsx, .pdf

This started happening since I changed the datacenter and migrated my server.
Actually I have already searched a lot of information about it and I do not know exactly what could be happening.