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Konstantinos Tsoukalas

Konstantinos is the founder and administrator of Since 1995 he works and provides IT support as a computer and network expert to individuals and large companies. He is specialized in solving problems related to Windows or other Microsoft products (Windows Server, Office, Microsoft 365, etc.).


  1. Alan
    May 10, 2023 @ 8:17 pm

    Had worked for ages from the old days when you could send through Gmail's SMTP servers then found increasing issues so changed to use the SMTP server for my external domain. Generally worked OK for a few days but then started getting immediate bouncebacks from Google with the 550 error above. Interestingly when I'd changed to use the 3rd party SMTP servers I was never sent a confirmation code. I'd had that years ago when first setting it up but clearly it meant it was in some in-between state! My solution was to delete the alias altogether and re-add it – that seemed to do the trick and no more 550 errors.


  2. Andrew
    December 23, 2021 @ 11:48 pm

    P.S. I tried Unsecured connection with Port 25 option, but then I can receive mail into Gmail my domains address, but can not send out (no outgoing). When I select TLS or SSL with the other 3 digit ports, any combination of those, I get a different error from Google,m but nothing works as it were.


  3. Andrew
    December 23, 2021 @ 11:45 pm

    Thanks. I tried all that. The problem persists. My host, the company that hosts my website, of which email I need to use as MAIL FROM AS, is trying all kinds of approach but they are unable or are unqualified to help. I used Gmail for many years and used my domain mail from Gmail without this problem. This problem started when I moved my website to a new server, at the same host, but instead cpanel it is now Plesk.


  4. Yoel Greenberg
    January 17, 2021 @ 9:38 am

    Thanks. Gone through all these stages. The problem persists.


    • Moshe
      April 14, 2021 @ 9:27 pm


      It used to be that you were able to get an app password with the 2-step verification on, and that these passwords would be remembered even after turning the 2-step verification off.
      Now all passwords are lost when turning off the 2-step verification off, so you basically have to leave it on the whole time and create new app passwords for each sending mail as is alias.

      Hope that helps.


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