I have created an alias to my outlook.com email account. The alias is of my corporate email ID. The alias was created without any issues, and the alias was configured for 'send and receive'. The 'send and receive' function is working fine from the webinterface of outlook.com. 

Now, I configured the corporate email ID in my email client, MS Outlook 2013. The configuration was done with the auto-sync facility available with MS Outlook 2013. The sync is working wonderfully well in receiving mail (pop). But incase of sending mails, some of the mails, especially the one with attachments are not getting delivered. I understand the actual process happening in like this - Outlook 2013>Outlook.com>My Email Alias SMTP Server. Somehow the system is failing in some mail deliveries.

I used another of my corporate ID in the similar fashion but this time with another email client. I configured the email client as POP and SMTP, and not auto-sync. The POP server used was pop3.live.com, with my email alias accessing the pop server. The system is working fine without any issues.

The SMTP server has been configured as smtp.live.com with port 587, SSL/TLS. Here, the problem starts. Some of the mails are getting lost, especially with attachment.  understand the actual process happening in like this - Outlook 2013>Outlook.com>My Email Alias SMTP Server. 

But if I change the SMTP server to my corporate mail server, smtp.domain.com, the system works wonderfully well, with 100% mail delivery, even with attachments (including heavy attachments). 

Somewhere the system of Outlook 2013>Outlook.com>My Email Alias SMTP Server is becoming unreliable. 

CAN SOME ONE HELP ME BY THROWING SOME LIGHT OR RECTIFY THIS ISSUE. 

Why I want to route my mails through outlook.com?

1. Has larger capacity than my corporate mail.

2. Has better features to sync with other devices.

3. Backs up mail even if my email client corrupts (which my corporate smtp sever never does). 

4. Quick to access using webmail option.

5. Integrates with my social network. Hence, with a single log-in I can perform multiple task.