Macmail switching to MD5 challenge-response
Hi. My mac mail keeps switching its authentication from password to MD5 challenge-response. It seems only to be messing up one of my two email addresses, and it keeps changing from not sending to not receiving, all very arbitrary. I change it back to password, and have tried quitting mail, restarting the computer, and the authentication keeps switching back to MD5 challenge-response. Any ideas? Thanks.
IMAC (RETINA 5K, 27-INCH, LATE 2015)