My internet service provider for many years has been Internode. Late last year they stopped providing free email service and addresses. They gave customers the option to use another email provider or migrate their existing Internode addresses to The Messaging Company, an Australian email mob. Part of that deal was that it would be free until sometime this year. After that date, migrated customers will have to either find another provider or start paying TMC for the email service. I haven't seen anything about TMC's performance that would make you feel like paying them, so I'm in the process of changing over to the free Google owned one. What a task that is. I've got a big list of accounts I hold which have the Internode address tied to them. Most of them require the email address as part of the login procedure.
Some companies don't have an option to edit the email address, so the only option with those is to set up a completely new account. With others, the changeover procedure takes a fair bit of time. You have to log in to your account then play a game of hide and seek to try to find the right settings. Some sites are so un-intuitave that the quickest way is to google how to find the settings. Once you finally track the settings down, you change the email address and wait for them to send a confirmation email to the new address. With Thunderbird, the quickest way to receive that email is to close Thunderbird then reopen it, in which case it will try to download any new emails. Once you get the confirmation email you might have to only click on a link in the email to verify it. With other sites, you have to copy a code, return to the browser page where you were changing address, then paste the code in a box and proceed from there.
So far, it's three down and a squillion accounts to go. It's going to be a long week. I won't miss the Internode addresses as they have a subdomain in the address added to an already long name. The length of it makes it a pain when you are continually typing it to log in somewhere. Trying to read out the address to someone over the phone is time wasting unless you spell it out in the phonetic alphabet. Internode was taken over by TPG some time back, and sometime this year they will cease to exist and we will be direct TPG customers.