To upgrade to mail2 would be as specified in the manual for the pop3connector upgrade procedure:
yum swap -- remove nethserver-mail-{common,disclaimer,filter,server} nethserver-getmail nethserver-spamd -- install nethserver-mail2-{common,disclaimer,filter,server,getmail}
But first we should find a way to make yum work again, and I’m not sure how.
Is there enough free space on the partitions for temp/cache files?
df -h
Probably it’s OK, but If you don’t mind sharing yum.conf file content:
cat /etc/yum.conf
Some other checks (share results):
rpm -qa python rpm* yum* # get packages version
rpm -qaV python rpm* yum* # verify file properties against rpm database
yum --noplugins check-update # try yum without plugins (probably will make no difference, but just in case)
yum --setopt usercache=1 check-update # try with the reported usercache attribute
Another idea is to check yum history for some mistype or copy/paste error that could have lead to this situation. See if you spot something:
yum history info <transaction ID number or * wildcard>