Windows 10: I am getting an 550.5.1.0 error when sending a message in Outlook

Getting a 550.5.1.0error when sending a message in Outlook. this has been happening for days. I am on vacation in Las Vegas. Can someone help me!!

:)

 

Outlook 365 Fails to send message 0x800ccc0F

I am using Outlook version 1812 build 11126.20196. This morning a wrote an e-mail and my system is unable to send it, I keep getting error 0x800ccc0f or 0x8004210B. Outlook keeps trying to send this e-mail over and over again. I have looked out those codes and followed the suggestions, even re-installed office and nothing helps.

I wrote the same e-mail again and it was sent out with no problem. I would like to delete this e-mail that is causing the problem, but it is NOT in the outbox. *cry I am getting tired of this send/receive error messages.

Help please,
Ak

 

How to stop Win 10 with Outlook sending attachments as Winmail.dat

WIN 10 (64 bit) with OUTLOOK 2016 send E-Mails which some recipients are unable to open or read.


The problem most commonly encountered, to judge from many internet pleas for help, is that normal e-mail messages are sent and received satisfactorily but attachments – whatever their file extensions – are sometimes apparently not sent or not openable. There are also reports that some e-mail main texts are apparently not sent or not openable. This note is based specifically on WIN 10(64) plus OUTLOOK 2016, but my extensive reading for a solution has revealed that other WIN / OUTLOOK issue combinations also give rise to the same or similar problem. It may therefore well be possible that the following actions will also be of assistance with these.
The root problem is that OUTLOOK sometimes encodes messages and/or attachments as WINMAIL.dat files and sends these. Many non-MS mail programs can not recognise and/or open these. WINMAIL.dat is a format used in times past for sending Rich Text Format (RTF) messages. I am uncertain why MS persists with this heritage I have found in limited testing that some ISPs seem to receive OUTLOOK attachments OK (because these are sent as their original files with “normal” extensions) whereas another ISP appears to prompt their conversion to WINMAIL.dat and then can not open them. I have, by the way, eliminated any possibility that the problem stems from my receiving computer. My accounts are of the “web based” type and I can open my E-mail boxes by web access direct to the ISP.
My testing (not comprehensive) has shown that when OUTLOOK is used to send attachments to a Gmail.com account they are received OK but when the exact same attachments are sent to a BTInternet.com they are received as WINMAIL.dat encoded files. It is thus doubly unsatisfactory in that one can not rely on the receipt of attachments sometimes, but not always.
Here are the 3 steps I took :- 1.. Modify the registry to inhibit generation of Winmail.dat files. To do this a.. Open program REGEDIT (Windows key plus R) b.. Go to Computer/ HKEY_CURRENT_USER/ SOFTWARE/Microsoft/Office/16.0/Outlook/Preferences c.. Create a new DWORD(32bit) called Disable TNEF
d.. Enter a value of 1 ie.0x00000001 (1) e.. Exit Regedit 2.. Set up OUTLOOK so as NOT to send messages in RTF format. a.. Open OUTLOOK b.. At top left SLCk the blue FILE tab. File page opens.
c.. In list at LHS SLCk OPTIONS. d.. From OPTIONS find and SLCk MAIL. e.. In MAIL option scroll down to COMPOSE MESSAGES f.. Find CHANGE EDITING SETTINGS g.. Select PLAIN TEXT format option in box. (HTML option may also be OK but RICH TEXT FORMAT – RTF – must NOT be selected). h.. Close the MAIL options page(s).
3.. Set up OUTLOOK not to auto-complete addressees and empty the auto complete cache. a.. Open OUTLOOK b.. At top left SLCk the blue FILE tab. File page opens. c.. In list at LHS SLCk OPTIONS. d.. From OPTIONS find and SLCk MAIL. e.. In MAIL option scroll down to COMPOSE MESSAGES
f.. Select SEND MESSAGES section. g. UNCHECK box labelled “Use auto complete list to suggest names when typing To/cc/bcc lines”. h.. Find and SLCk the “Empty auto complete list” i.. SLCk YES in response to “ARE YOU SURE” pop-up box j.. There is no apparent response to step i. k.. Close OUTLOOK mail option page(s). l.. For good measure re-start the PC.

Notes : i.. At step 3e with OUTLOOK 2013 scroll to SENDING MESSAGES section. ii.. In OUTLOOK 2003 and 2007 for procedure section 2 : iia.. Access OPTIONS from the tools menu iib.. Click MAIL FORMAT tab iic.. Click INTERNET FORMAT iid. Under Outlook Rich Text Options click either Convert to HTML format or Convert to Plain Text format. Get rid of any reference to RTF.
iii. This note is written based on Win 10(64bit) plus Outlook 2016. Other OS/Outlook versions may vary in function and detail.
iv.. Some versions of OUTLOOK provide for the message sending format to be varied between addressees in the address book. To check for this each address book entry needs to be examined from its PROPERTIES values. These should be opened and set to HTML or PLAIN TEXT and never RTF (or TNEF). v.. With my problem the solution was achieved after step 3. It appears that the auto-complete cache “remembers” previous settings and hence it needs to be deleted.
vi.. Step 3 was the vital action and was kindly contributed by Caledon Ken at TEN FORUMS I will mark the thread as resolved after further evaluation, but am highly optimistic. .

 

Outlook Cannot Send Mail


I have tried the above twice and still unable to send from Outlook 13 (Office 365)(Win 10). I have deleted 2 read receipts which were stuck in the outbox. Still cannot send.
I have several Gmail accounts running fine from same Outlook.
The error message says
"Sending reported error 0x800CCC0FServer responded: 550 isn't on our network to be able to send mail"
Have checked this error code with MS and it comes up with information from 2003! XP!
Have run the scan twice and rebooted. No Faults found.
Any help gratefully received.