Enabling someone else to access and use my iCloud email

The safest thing to do, and is what I would do, is create a new email just for your business. This can simply be a new Gmail account. Then, that's all it's for and it doesn't matter that your assistant knows the password.

But the necessity of sharing your Apple ID and password for her to access your iCloud mail account is a bad idea. No matter how trustworthy that person is, things can change.

Yes, it's a bit of work to contact all of your clients and vendors to update them with a new email address, but that can be done in one bulk CC copied email. Give them a two week notice that all further emails should be handled at the new address.

There are various ways to go after this problem, and you're at the difficult size — too small to have IT, and with the problems that entails.

Sharing your own Apple Account is possible, but is decidedly not a good choice, not recommended, not supported, and can be a disaster waiting to happen.

I'd be looking to set up a shared email account, or maybe a customer relationship management system.

The CRM approach has the advantage of allowing everybody to access the customer info and to incoming mail, meaning vacations are automatic. It also means others can't accidentally or intentionally clobber your email accounts.

https://crm.org/crmland/what-is-a-crm

https://crm.org/crmland/open-source-crm

Most CRMs can be hosted, which gets you out of the business of managing most of the issues that can arise.

If you choose to share an email account, I'd likely create a task-specific Apple Account (or gmail or whatever), and share that. That avoids ceding full control to your Apple Account. You can both access the shared account.

You shouldn’t share your iCloud email and password with others, see here -> Use Custom Email Domain with iCloud Mail - Apple Support

Add or remove people sharing a custom email domain on iCloud.com - Apple Support

It depends on what email client she's using how you would add the account. It can vary quite a bit between Apple's Mail app, eM Client, Outlook, etc.

When adding the new account, she would (of course) put your email address in the address line. Then the other fields are filled in as below for an icloud.com account:

IMAP information for the incoming iCloud Mail server

• Server name: imap.mail.me.com
• SSL Required: Yes
  • If you see an error message when using SSL, try using TLS instead.
• Port: 993
• Username: This is usually the name of your iCloud Mail email address (for example, johnappleseed, not johnappleseed@icloud.com). If your email client app can't connect to iCloud Mail using just the name of your email address, try using the full address.
• Password: Generate an app-specific password.

SMTP information for the outgoing iCloud Mail server

• Server name: smtp.mail.me.com
• SSL Required: Yes
  • If you see an error message when using SSL, try using TLS or STARTTLS instead.
• Port: 587
• SMTP Authentication Required: Yes
• Username: Your full iCloud Mail email address (for example, johnappleseed@icloud.com, not johnappleseed)
• Password: Use the app-specific password that you generated when you set up the incoming mail server.

Much of the above is filled in automatically, depending on the mail client in use.

The password would be the one you already have established, so skip the link about generating one.

All you need to do is add an account to her email client to access your business email address. The assistant does not need access to your actual Apple account.

Normally, they are. But you can also make the password for the email access different. Something you may want to consider so your assistant can't access your entire iCloud data (photos, contacts, messages, etc.).

How you would change only the email password I can't say as I've never used Apple's mail server.

It also doesn't help that some links I found say yes, they can be different. But more say no, they're one and the same with no way to separate them.

Hopefully, someone else here who does use @icloud.com can confirm one way or the other.