smtp definition

You need to phrase your question so it can be understood. You are 100% clear on what you want to know, but that has not transferred to your post. Please read Writing an effective Apple Support Communities question

If you are hoping that you are addressing Apple, you are not. This is a user to user forum. No-one here has any idea what is in Apple's mind

Mac Mail works well for the vast majority of users. Some have problems with it. I run 10 different accounts with several different server types, and have no difficulties. You may find https://support.apple.com/en-gb/guide/mail/cpmlprefsmtpserver/mac to be helpful if you are having problems.

I take it you didn't find the guide of use?

I have 10 email accounts, most are IMAP, though on different servers. One is POP3, one is Exchange. They all work and have for many years.

The key was setting each up slowly as a full process, including associating the correct SMTP server with each account for outgoing mail, and setting the correct ports ad security settings where relevant. I set up one account, then my next, and so omn until all were finished

You can use the same SMTP server for two different accounts is that is valid, and you can do this today

I very much doubt a new release of OS X will solve issues if they are setup issues.

If you go into Mail ->Preferences in the Mail application and then go to the Accounts Tab, you can set properties for each e-mail account. Under Server Settings menu item, you can specify the outgoing mail server to be used. You can also specify the Reply-To address (Make it visible in the View menu.) which the recipient will automatically use for replies.

Safari normally reopens all windows and tabs that were open when you last closed Safari. If you hold down the Shift key while opening Safari, it won't reopen the windows. In the Safari->Preferences menu item in Safari, open the General Tab and it allows you to set new windows and tabs as an empty page, the Favorites page, the most used page, home page, etc.

MacOS Catalina and ios 13 are problematic (to be charitable). However, I have seen problems like this before and believe that upper management is aware of the problem. However, a bad MacOS release is still better than a good Windows release, in my opinion. If the timing of the last few releases continues, we can expect 10.15.2 soon. I strongly suspect that heads have already started rolling.

Do you have a question for us? Generally that is what the forums are for