Gmail: add another email address: Authentication failed. Please check your username/password and Less Secure Apps access

Question

When you try to "Add another email address" in your Gmail settings you may end up with the following error message:

Authentication failed. Please check your username/password and Less Secure Apps access for xxxxx.

The "Show error details" may show the following:

Server returned error: "534-5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbsy 534-5.7.14 GPIEivKVfyr4lasdf8cHAo8iIp26aW-3G-kqVf_Zug 534-5.7.14 HFve2asdgPmPuG2GfmiuU3EsdaZVeJcoZa-IvocTK-Dy74CSCk5lBJBE-Wd5sjnYzuJ872ySbCz8 534-5.7.14 xFIECagaMP0z5IP4GfrU3rYRFmmW2asd85W2rSDTe 534-5.7.14 e1m9WLZkBsadgCl_9ykOZARoF3QjDnGQ> Please log in via your web browser and 534-5.7.14 then try again. 534-5.7.14 Learn more at 534 5.7.14 https://support.google.com/mail/answer/78754 r29sm8740195edl.82 - gsmtp , code: 534"

Answer 1

Google has added new security feature. This is if you wonder why this did work before and doesn't work now.

The feature is about "less secure apps".

You have two options now:

1. allow access for "less secure apps". Follow google how to do it
   Then use smtp.gmail.com as SMTP server and your gmail username and password. Keep the "alias" option on.

2. Use your own SMTP server. If you have own custom email other then gmail then you might have a hosting with it. Hosting is not mandatory part for custom domain but if you have a web then you have a hosting. With hosting there usually go also email accounts and associated SMPT server. Ask you hosting provider to get one for you.