"Message failed to send" Red Error box in Outlook 365 for Mac

The only thing that works for me at this point is to use the online version. It saves as a draft when it doesn't send, but deletes all recipients. It's such a pain!

Sucks that this has to be done just to send an email from Outlook... This plagues me all day long.

Hi everyone - has anyone had issues with sending emails using Outlook 365 for Macs? Especially a red error box that appears at the bottom (attached) and says "Message failed to send Open" The email is then stuck in drafts with the option to continue editing but it is simply frozen in drafts and the only way is to delete and try again. Alternatively, you can go to the webmail version of outlook, find the drafts folder and send from there. This has been happening on/off for several weeks now, no pattern, just happens occasionally.

This version of Outlook 365 is absolutely **** with so many issues

Got it solved! Basically, all I did was:

1/ Restart outlook

2/ Go to the email having a sending problem and delete it. (Do copy your content first)

3/ Hit Reply/Reply All again

4/ Skim through the email body to see if there are any images in signatures missing or not loading (this indicates the email is pending a loading job)

5/ If no image is missing, hit send.

6/ If yes an image is missing, delete that image, and hit send.

Worked for me. Good luck all.

Multiple people in my organisation are having the same issue.

I suggest everyone who is having this same issue open a support ticket, Microsoft does not appear to be listening to this thread.

That's when I found this thread. When support told me to raise it here and wouldn't raise an escalated but ticket or similar. :-/

Multiple people in my organisation are having the same issue.

I suggest everyone who is having this same issue open a support ticket, Microsoft does not appear to be listening to this thread.