In gmail, you can set up priority inbox, but apart from that, I don't think so.
When the contents of the email are of high priority to the recipient.
The Priority ! - High Priority
In Yahoo Mail, you can send high priority emails by marking them as "High Importance." When composing a new email, click on the three dots in the toolbar at the bottom of the email composition window and select "Set High Importance." This will flag the email as high priority for the recipient. Keep in mind that the recipient's email client settings will determine how prominently the email is displayed as high priority.
The types of email marketing services available to businesses are: Sending emails to the businesses' customers, sending emails to acquire new customers, and adding advertisements to emails sent to other businesses' customers.
Most email softwares ared free and don't actually cost you anything but if you want to pay for email software you can check out Juno and Gmail and a school email
Exclamation mark is a high priority email. Down arrow is low priority. Nothing (no sign) is normal priority.
What are the two commercially available email tools?
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Priority is a mechanism that concept is used when two or more process being processed at a time. In other words we would say "which process can be right to executed first among two or more processes" Generally priorities are several type. but system oriented types are 1. Static priority 2. Dynamic priority
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By doing research about what types of marketing is available and caters specifically to email businesses you will be able to narrow down possibilities and better choose the best option for your business.
Depends on email size!