I have 4 different email accounts, all managed by IONOS. These have all been set up under thunderbird OK. But when I send an email from 1 of these email accounts I always have to enter my password for that a/c. With all the other accounts, this is not necessary. I do not use Thunderbird or Firefox password managers. I assume that I must have made an error in setting up the outgoing details when setting up that particular account in Thunderbird, but I cannot find a way of checking if that is the case.