Ok lets correct the terminology... it is not an alias. It is a mail account. Why you do not just add it to thunderbird as an account I do not know.

Now we have correct terminology the way to make it work with both outlook.com and Gmail.com are in their own instructions.

Outlook.com https://col430-sec.mail.live.com/mail/AggregationSetupAdvanced.aspx?SEP=Options&mode=AddSendOnly&auto=False&n=927376096 Gmail.com https://mail.google.com/mail/#settings/accounts See the send mail as section.

Thanks for your reply. I only registered a domain name with 123reg and they forward any mail sent to something@mydomain.com to any other email address. I'm not paying 123reg for an actual email hosting....sorry if I have the terminology mixed up.

I have one set up with gmail and it does send emails as something@mydomain.com, but they've stopped it for any new registrations. That's why I'm looking for another email provider which would allow this.

Or any other way in which I can send emails as something@mydomain.com.

Please I am trying to understand, but when I go to the 123 site, even their lowest tier of domain hosting offers ;

Only £1.99 per month

For the first year, Then £2.49 per month

Mailboxes100 Mailbox size1GB

I can not see one that auto forwards mail, and any package that has email attached will also have SMTP for sending mail.

Later addition. I have found instructions on their web site, perhaps you could try them. https://www.123-reg.co.uk/support/answers/Video/Email/how-to-set-up-my-email-with-thunderbird-4979/

If you go on this link: https://www.123-reg.co.uk/domain-names/ and choose domain features, you should see what I have signed up for. I have just registered my personal domain under their 'Professional email addresses', which allows a forward to be set up, but no mailbox or webmail.

Because I don't have a mailbox, I can't use their SMTP settings to send mail....I was hoping to cut costs and not sign up to a mailbox, but use a free email service to do this.

I hope that clarifies my situation...