emails getting stuck in outbox intermittent

I use Yahoo email with POP forwarding to Outlook, and have for several years, but this is the first time I've experienced this problem. I'm not tech savvy and am incredibly frustrated by this whole experience, so I'm obviously looking for an easy and quick solution (I guess this is not possible in a Microsoft universe.). I assume this has something to do with my ISP (AT&T U-Verse DSL) and not my email client but I don't know. The mail server or Outlook becomes offline. The Outlook account is not authenticated by the mail server. The email is marked as viewed in the Outbox due to an installed add-in. Emails get stuck due to large attachments that halt or slow down the sending.

New messages cause no problems, just replies. Here, we have noted the most common reasons due to which emails get stuck in Outlook Outbox. Some replies go, some don't, but there's no consistency to it. The original messages is still stuck in Outbox. You can forward the stuck message to the same person, hit Send/Receive, and the forwarded message goes out fine. Other messages send/receive around this one, but this one message will not send. Oddly enough, this is an intermittent problem. The message does not send and just sits in Outbox. When I get a message and try to reply, it sits in the Outbox indefinitely. In addition, I'm sometimes unable to respond/reply to email as well. fewer steps) than either of these that will correct my problem. I downloaded both apps to correct this problem, but to no avail.

My Outlook 2003 started with the 'sending 1 of 2' about three weeks ago, and has now increased to 'sending 1 of 11'. Unfortunately, I'm getting this message with both Outlook Spy AND MDBVU32. I'm getting the exact same error message: IMsgStore::AbortSubmit() returned MAPI_E_UNABLE_TO_ABORT.

Emails getting stuck in outbox intermittent