Send as IMAP account not clearing messages from OUTBOX.

Well, I'm not looking for a new way of working with Outlook and sending messages out of the Outboox works JUST FINE FOR POP and EXCHANGE. I'm looking for a fix for Outlook so that my IMAP accounts work, as my POP accounts already do. When I used POP all was fine, and still is with POP accounts that I still have. It's ONLY IMAP that's giving me problems. THESE MESSAGES NEVER CLEAR THE OUTBOX.

I am using Outlook 2013, but I think they are very similar. Below is a copy from the Outlook Help files that may help you. I have highlighted in red an item that may relate to you IMAP not working.

Add an email account with custom settings or when automatic setup doesn’t work

If you’re setting up Outlook for the first time or you’re adding a new mail profile, and the Account Setup wizard doesn’t finish successfully, there are some things you can try:
##You can wait a while and try again. Sometimes, a mail server might just be having a temporary problem, or there’s a network connection issue.
##If trying again doesn’t work, you might contact your email administrator (if you’re in an organization). There may be problems you aren’t aware of, or you may need to use some custom settings.
##If you don’t have an email administrator, take a look at the When Outlook can't set up a new profile by using Exchange Autodiscover knowledge base article for help.
##There are some mail accounts (such as Yahoo! Mail) that can’t be used with Outlook unless you upgrade to their subscription plan. Check with your email provider to learn about upgrading.

Some types of mail accounts — like those you get with your broadband internet service, or web-based mail — might require you to change the default value for the port number for outgoing or incoming messages, or enter a specific URL for the server address. See the section Set up the email account for detailed steps on setting up your account manually.

Set up the email account
1.Click File.

Screenshot of left section of Outlook ribbon with File selected
2.Click Add Account.

New Account button in the backstage view
3.Click Manual setup or additional server types > Next.

If you’re not sure whether you are using a POP3 or IMAP account, contact your email provider. You may also need to change the outgoing or incoming port number for your account. See the section Commonly used ports in POP3 mail systems for more information.

POP3 or IMAP account
1.Click Internet Email, and then click Next.
2.Under User Information, do the following:
1.In the Your Name box, type your name the way you want it to appear to other people.
2.In the Email Address box, type the complete email address assigned by your email provider. Make sure to include the user name, the @ symbol, and the domain name, for example, pat@contoso.com.
3.In the Password and Retype Password boxes, type your password.

Tip Passwords are case-sensitive. Make sure the Caps Lock key isn’t on when you enter your password.
3.Under Server Information, do the following:
1.In the Account Type list, choose POP3 or IMAP.
2.In the Incoming mail server box, type the full name of the server for your email provider. For example, mail.contoso.com.
3.In the Outgoing mail server (SMTP) box, type the full name of the server for your email provider. For example, mail.contoso.com.
4.Under Logon Information, do the following:
1.In the User Name box, type your user name. This might be the part of your email address before the @ symbol, such as pat, or it might be your complete email address, such as pat@contosco.com.
2.In the Password box, type your password.
3.Check Remember password.

Note If you choose to let Outlook remember your password, you won’t have to type your password again when using Outlook. Anyone who has access to your Windows computer account can read or send mail as you.
5.Your email account might require one or more of the following additional settings. Contact your email provider if you have questions about which settings to use.
##SMTP authentication Click More Settings. On the Outgoing tab, check My outgoing server (SMTP) requires authentication. You may need to change the port number, depending on your email provider. Check with your provider for details.
##POP3 encryption For POP3 accounts, click More Settings. On the Advanced tab, under Server Port Numbers, under Incoming server (POP3), check The server requires an encrypted connection (SSL). You may need to change the port number, depending on your email provider. Check with your provider for details.
##IMAP encryption For IMAP accounts, click More Settings. On the Advanced tab, under Server Port Numbers, under Incoming server (IMAP), for the Use the following type of encrypted connection option, click None, SSL, TLS or Auto.
##SMTP encryption Click More Settings. On the Advanced tab, under Server Port Numbers, under Outgoing server (SMTP), for the Use the following type of encrypted connection option, click None, SSL, TLS or Auto.

Note Most email providers use port 465 as the default for outgoing messages and port 995 for incoming messages.
6.Click Next.

By default, Test Account Settings by clicking the Next button is checked. This option verifies your account is working. If any information is missing or incorrect, you’re prompted to enter or correct it.
7.Click Finish.

Microsoft Exchange Server account

Important In most cases, you won’t need to manually configure your account if you connect to an Exchange server. We recommend trying again if your first setup attempt fails, and then contacting your Exchange administrator if that doesn’t work. You can try the following steps:
1.Click Manually configure server settings or additional server types, and then click Next.
2.Click Microsoft Exchange, and then click Next.
3.Type the Exchange server name. Your Exchange administrator can give you this name.
4.To use Cached Exchange Mode, check Use Cached Exchange Mode. Cached Exchange Mode allows you to work with items in your Exchange mailbox even when your network connection is slow or unavailable.
5.In the User Name box, type your user name.
6.Optionally, do any of the following:
##Click More Settings. On any of the tabs, select the options you want or your Exchange admin tells you to change.
##Click Check Names to verify the server recognizes your name and your computer is connected to the network. The server and account names you specified in steps 3 and 5 should become underlined. If your name isn’t underlined, contact your Exchange admin.
7.If you clicked More Settings and opened the Microsoft Exchange Server dialog box, click OK.
8.Click Next > Finish.

Maybe this might help?

“If you are using IMAP, you need to either turn off automatic send and receive or make sure that the IMAP account is not included in that. Automatic send and receive interferes with the IMAP update which happens separately.

To explain the option:
* If your IMAP account is the only account you have, then you can simply turn off automatic send and receive because it is unnecessary.
* If you have other email accounts that are using POP, you will probably want them updated regularly, so leave on the auto s & r for them, but disable it for the IMAP accounts. You could also just do the s & r manually.”

This seemed to help with my sync issue, and I am still receiving emails.
However, when i send emails, they go to “Outlook Data File” “Outbox” and then I have to click “send all” and wait for messages to send.

Source:

Add Your Gmail Account to Outlook 2010 Using IMAP