Some Workflows stopped sending mails

Some Workflows stopped sending mails

Hello to all!

For months I have been using several workflows to automatically send mails to business partners and customers when certain conditions in the Deal are met.

Since the 23rd of December no more mails are sent for some, but not all, workflows.
The curious thing is that the triggers for the still working ones are the same.
So the system seems to have a technical problem since that day.

Can anyone help me with this or does anyone know this problem?

Many thanks in advance,

Alex