Email MS Outlook won't send message. Mesage gets hung up in Outbox. Error messaage (0x800CCC78) 550 5.7.1 Authentication Reuired

Unable to Send Email? Check These 5 Things - rackAID

https://www.rackaid.com/.../cannot-send-email-how-to-fix-email-sending...

This likely means SMTP authentication is not enabled. If you get a relay denied error and your password is correct, then SMTP authentications is likely not correct. Often, email users with this issue can receive but cannot send email.

I am receiving email fine, but I cannot send messages ...

www.gn.apc.org/.../i-am-rec...

Association for Progressive CommunicationsThe usual symptom is that Thunderbird will try to send for about 20 seconds before giving up with "Sending of message failed. The message could not be sent ...

Are you able to receive emails but not send? - Hostgator.com

support.hostgator.com > ... > Email > Email Troubleshooting

If you aren't able to send email, this usually means one thing: your internet provider is blocking you from using anyone's outgoing mail servers but their own. ... so that theycan monitor outgoing email on their network in order to prevent spam.

Problems Sending Mail - Receiving is Fine - InMotion Hosting

www.inmotionhosting.com > ... > Email > Email Troubleshooting

Jan 14, 2015 - Outlook 2013, cannot send mail, but can receive mail ... I haven'treceive any mail since yesterday and I can't send mails too... can you help me ...

I can receive emails but i can't send them. ' Apple Support ...

discussions.apple.com > Support > Apple Support Communities

Apple

Reinstall the email program, first clean up the computers registry with Ccleaner then install fresh version of your email program.
http://filehippo.com/download_ccleaner/
download link it on the right side of the page, use both cleaner and registry.

Wait until it unfreezes

This is one way I've found to delete an email stuck in the outbox (which is what it "sounds like" you are asking...)

1. change ya smtp settings so the message defo wont send!
2. send a test email to anyone
3. it will attempt to send but oversiously fail...
4. hopefully the outbox should be listed with 1 message waiting to go out...
5. if not, try going into the Activity Window and canceling the send command, that should show it up...
6. click the Outbox and the will be one message listed...
7. goto View -> then Show Favourites Bar
8. you should see a favourites bar appear...
9. simply drop and drag the Outbox into your favourites bar...
10. if you restart ur laptop or close mail and then the Outbox has disappeard, simply click the Outbox in you favourites tab and woop woop it should appear in the Side Bar

Once you know you are in an arts with a strong enough signal, re-sync. It should not only check for new, but also send all waiting emails.

Contact their supports at: http://www.blue-yonder.com/en/contact.html

Maybe, try setting-up a second Gmail account, then send transfer) your emails from the old username account to the new username account. If this works, then either try deleting the messages from the old gmail account and transfer the messages from the new gmail account back to the original gmail account ... or ... just delete the old gmail account if you successfully transferred them to the new gmail account.

Your problem is not with the tablet but with the email client. You need to connect the client on the tablet with a valid email account that you have elsewhere. The email account will have details to help you do this.

When sending emails, while on the move (i.e using different wireless or broadband connections), if you do not click authentication required for the outgoing server and enter the username and password, or click use the same as incoming server the emails will not successfully deliver. It all depends on which email provider you are using.