Sometimes, your mailbox database does not visually reflect reality. If you have a situation like a deleted message still appearing in your Apple Mail account, you will probably see an error message. A database is a binary blob of information, so it may need to be updated via a rescan from time to time. In the Apple Mail app, select the particular mailbox in the sidebar, then choose "Mailbox" and "Rebuild" afterward. Your mailbox may appear empty until the attachments/messages are all downloaded back to your device.
Greg has email messages that he can't throw away. When he tries to trash it, he gets an error message. He's using Apple Mail. Leo says the message is actually deleted, but the entry is persisting for some reason. Within the mail app, select the mailbox in question and rebuild it. It will rescan the database and rebuild the index. Here's how - https://support.apple.com/guide/mail/rebuild-mailboxes-mlhlp1227/mac
Dave has an email account that has been hacked and now he's getting requests for new passwords. He found out by noticing the forward codes after the request. Leo says that it's a common scam. Fortunately, Spectrum changed his password for him. But now Apple Mail can't make a connection with the new password. Leo thinks that the email client may not like the password. So Dave could try changing the password again. But Spectrum may have turned on a feature that limits what Dave can do to protect him. What Leo suggests is to delete your email account and then set it up again.
Joe has a 2009 iMac with a bunch of emails on it, dating back to 2003. He wants to know how to open them in another email program, along with the contacts as well? Leo says it varies according to the email program you use. Leo says that since Apple Mail exports to MBox, you can open that format into just about any other email client. You can even open them in a text editor to see what's in it. Apple Mail will import them easily, and Thunderbird should be able to as well. Leo also recommends using SuperDuper to back them up.
Linda is frustrated that some of her contacts always end up in the spam filter. Leo says that somewhere the email program learned that those contacts were sending spam, and it may be due to the content of the email. Leo recommends setting up a separate filter that will keep those contacts in the inbox. They may also be called "rules."
Kevin would like to select and delete multiple emails in Apple Mail on the iPhone. Just tap "edit" and then mark it, move it, or trash it. Leo says that one of the problems with the modern iPhone is that there's no standard user interface like the old Macs. That makes it difficult to do things like this when the UI changes.
Terry got a new Mac for an early Christmas present and is waiting awhile to reinstall stuff. Leo says that's a good idea. It's much better to only install new programs as needed. Every program he installs is a potential security risk, so he should install as little as possible.
Elise uses Apple Mail with her Gmail account and whenever she saves a draft email, it disappears. Rich thinks the culprit may be a corruption in the Apple Mail program itself. He recommends that she look in Gmail in her browser to verify is the draft emails are still there. They probably are. Then she can reset or rebuild Apple Mail. She may need to delete her email account from the app and then add it again.
Brian wants to know how he can use tags to stay organized on his email. Leo says that tags are great for searching and it makes it really simple to stay organized. Gmail can tag messages. Mailtags has been around for years and it works great. Leo used it a long time ago and it works in Apple Mail, which can be a challenge because Apple changes Mail with just about every version of macOS. It's also great for photos. Google Photos is great for tagging as well.