A quick note on terminology first. In an address like abc@domain.com shown as "abc xyz":
abc@ = the alias (the local part of the email address)
domain.com = the domain
abc xyz = the sender's first and last name (the display name)
Changing the first/last name (display name)
To change only the first and last name, without changing the email address itself, contact our support team. We can update this from our side without creating a new mailbox or starting a new warmup cycle. Once it's done and confirmed, you can download and re-upload the updated CSV to your sequencer if needed.
If recipients see only your email address and no name at all, it usually means the display name isn't set yet. Note that if you send through a sequencer, the sender name configured in that sequencer can override what recipients see — so check it there too. More detail: Profile picture and sender display name.
Changing the alias (the part before @)
The alias can't be edited in place. To change it, the mailbox must be deleted and recreated using the Add More Email Accounts option, and the new mailbox needs a fresh warmup period of at least 10 days before you send from it. Because this resets warmup, only change the alias when you really need to.