When you have domain name aliases setup for your email addresses, you might want to send your emails from a particular domain.

In this case, we want to send from @beezyeco.ca instead of @beezywrap.ca

You will still login to webmail with your previous address; ie @beezywrap.ca

But send from @beezyeco.ca.

Directions

Login to your email account through the webmail interface.

Bottom Left Hand Sidebar -> Gear Icon (Settings) -> Accounts -> Add an Identity

Fill out the form with your details. Your email address for this identity is info@beezyeco.ca, for example.

You will then see a list of identities in a table. The left most column of the table has a button with which you can move the identities up or down. Drag your @beezyeco.ca identity to the top to make that the default.

When sending an email, you can switch identities on the fly.  This might not be necessary once you setup your default identity but it is an option.  See the blue circle in the image below.