In order to use MassMailer Inboxing, you have to allow "less secure apps" in Gmail / G Suite / Google WorkSpace.


If the email account is on G Suite / Google WorkSpace, the "Less secure apps access" may be locked in the admin. Therefore, you will need to enable it in the Google WorkSpace Admin or ask your admin to do it (check #2).



#1. How to allow "less secure apps" on your Gmail account if the option is not locked:


Sign in to your Gmail account

Browse to: https://myaccount.google.com/lesssecureapps

Make sure you're on the right Gmail account by checking the account selector icon on the top right of the page.

Click Allow less secure apps on the switch

Visit the Display Unlock Captcha page and click Continue to remove the security block.


When going on the Display Unlock Captcha page, if you're connected to several Gmail accounts at the same time it may not be unlocked for the right account. To make sure you're not doing the unlocking on the wrong account, visit the Display Unlock Captcha page in incognito mode.



#2. How to allow "less secure apps" in the G Suite / Google WorkSpace Admin if the option is locked:


Sign in to your Google Admin console (Sign in using an administrator account).

Click Security > Less secure apps.

Select Allow users to manage their access to less secure apps.

Click Save.

Once it's done, you can allow "less secure apps" on the account you want to connect to MassMailer Inboxing as explained above in #1


#3. I've allowed "less secure apps" on both my email account and my G Suite admin but I still can't connect my account:


That must be because you've visited the Display Unlock Captcha page but you were connected to several Gmail accounts at the same time so you've allowed it on the wrong account.

Open your navigator in incognito mode, log in to Gmail with the account you want to connect to MassMailer Inboxing, visit the Display Unlock Captcha page and click Continue to remove the security block.