Previously mail manager on vTiger was working and receiving emails. One day ago it suddenly threw an error:
Retrying PLAIN authentication after [AUTHENTICATIONFAILED] Invalid credentials (Failure),
Retrying PLAIN authentication after [AUTHENTICATIONFAILED] Invalid credentials (Failure),
Can not authenticate to IMAP server: [AUTHENTICATIONFAILED] Invalid credentials (Failure)
Password and username are correct, checked them by logging into gmail.
Username: [email protected]
I also tried clearing the captcha, didn't help https://www.google.com/accounts/DisplayUnlockCaptcha
I tried installing a totally fresh copy of vtiger crm via softaculous app installer and it still threw the same error.
I then tried installing vtiger on a different server, and STILL it threw the same error.
I finally tried a new gmail address. Again it threw the same error.
But when i tried setting it in vtiger CRM on Demand, it worked.
In my situation the problem came down to the special characters in the password. After removing the special characters from the password it worked! (It even worked with _ but not with + so there may be a few options).