How to forward and send from a custom email alias — Gmail, Outlook, and Yahoo setup guide

“Forwarding” and “sending as” an alias are two separate things, and they work differently depending on which inbox you use. Forwarding — mail arriving at your alias — works identically no matter what you use as your destination. Sending asthat alias, so replies look like they came from it, is where Gmail, Outlook, and Yahoo genuinely diverge. Here's exactly what happens with each, without glossing over the differences.

Receiving mail: the same for everyone

This half doesn't depend on which inbox you use. Mail sent to your alias — say james@boldmail.cc— is received and relayed straight to whichever inbox you set as your destination during onboarding. There's nothing to configure on your end for this part; it's live as soon as your alias is verified.

Sending as your alias: three genuinely different setups

On Premium and Surname tiers, you also get SMTP credentials — a host, port, username, and password — from your dashboard. What you do with them depends on your inbox.

Gmail: uses the SMTP credentials directly

• Go to Gmail Settings → Accounts → “Add another email address.”
• Paste in your alias address and the SMTP host, port, username, and password from your dashboard, then save.
• We forward a short verification email to your inbox — click Confirm.

This is the one setup that routes outgoing mail through the actual relay, properly authenticated end to end. Recipients see it as sent from your alias, full stop — no “on behalf of” note.

Outlook: uses its own alias feature instead

• Outlook.com doesn't use the SMTP credentials at all. In Outlook, go to Settings → Mail → “Forwarding and IMAP” → Email aliases → “Manage or choose a primary alias,” then click “Add email” and add your alias.
• Outlook shows a “Verify” link and emails a confirmation to your inbox — your alias is already live and forwarding, so go ahead and click it.
• When composing, choose Options → “Show From,” then pick the alias.

Worth knowing up front: Outlook sends this “on behalf of” your main address rather than through our relay — it's Outlook's own alias mechanism, not ours, so the authentication story is different from Gmail's.

Yahoo: also its own mechanism, not the relay

• In Yahoo Mail, go to Settings → More Settings → Mailboxes, click the “More” icon next to “Send-only email address,” and enter your alias.
• Yahoo emails a verification link to the alias immediately — since it's already live and forwarding, click it right away.
• Once verified, pick the alias from the “From” field when composing.

Like Outlook, this sends from Yahoo's own servers rather than through our relay — a different mechanism again, and worth knowing if you care specifically about how the message is authenticated.

Which one to use

If sending exactly as your alias — with no “on behalf of” note and full relay authentication — matters to you, Gmail is the setup that delivers it. Outlook and Yahoo still let you reply looking like your alias with a couple of extra clicks; they just do it through their own native alias systems rather than our SMTP relay. Receiving works identically either way, from the moment your alias is verified. If sending isn't set up yet, Premium and Surname tiers both include it.