Email clients cannot send. Receive only sporadically.
High Sierra version 10.13.6
None of my emails in both of my email clients are working correctly. All of this began Sunday morning, October 13, when I turned my computer on.
At first, I called my ISP, thinking the problem might be on their end. We did some troubleshooting and did not fix the problem. I set up Outlook on a Windows laptop that I have and it worked as intended. Right now, my only assumption is that the problem is with my computer itself.
I have six email addresses in my mail clients. None of them are working correctly. None of them will send an email. Some will occasionally receive emails, but others are completely dead.
I have tried all my emails in both the Outlook client and the Mac Mail client. Both are behaving the same way.
The rundown is as follows (all are IMAP unless otherwise noted):
iCloud: Sometimes receives email. Cannot send email.
Work email (MS Exchange): Sometimes receives. Cannot send.
School email (MS Exchange): Cannot receive or send.
Hotmail: Sometimes receives. Cannot send.
Outlook: Sometimes receives. Cannot send.
Yahoo: Cannot receive or send.
Teksavvy (my ISP): Cannot receive or send.
The above problems are identical on both the Outlook client and Mac Mail client. All emails work just fine on my Windows laptop. All emails work fine in web browsers.
I installed a security update (2019-005) on my Mac on October 5.
The only thing I an reasonably sure about is that the problem is not with my ISP or internet connection, which leaves me with a Mac problem.
Can anyone help?
iMac Line (2012 and Later)