Starting January 2027, Gmail will no longer support the 'Send as' feature for third-party email addresses such as @yahoo.com or @outlook.com. This change does not affect Google Workspace aliases or other Gmail addresses you own. Users can still send mail from addresses they own by adding and confirming them in Gmail settings.

To send from another address, users must add the address, confirm it via a Gmail-sent message, and select it from the 'From' line when composing emails. Recipients may see the sender's Gmail address with 'on behalf of' notation if using certain mail services. To always send from a different address, users must change both the default 'From' and 'reply-to' addresses in Settings under Accounts and Import.

If an invalid alias is used, a bounce email will occur; users can remove or reverify addresses by deleting and re-adding them. For connection issues like 'Couldn't reach server' or 'TLS Negotiation failed,' users should verify port numbers, authentication types, and outgoing mail server settings with their third-party provider, prioritizing SSL/TLS with valid certificates for secure connections.