CodeIgniter default mailer unable to send email using PHP SMTP

Question

I am getting the following error while trying to send the email using the default CodeIgniter mailer. I have browsed the StackOverflow to find the solutions but none of the answers solved my issue. following is the stack trace.

220 smtp.gmail.com ESMTP x11sm47816605pfn.53 - gsmtp
hello: 250-smtp.gmail.com at your service, [xxx.88.xxx.16x]
250-SIZE xxxxxxx
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
starttls: 220 2.0.0 Ready to start TLS
hello: 250-smtp.gmail.com at your service, [xxx.88.xx.16x]
250-SIZE xxxxxxxx
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8


Failed to authenticate password. Error: 535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8 https://support.google.com/mail/?p=BadCredentials x11sm47816605pfn.53 - gsmtp
Unable to send email using PHP SMTP. Your server might not be configured to send mail using this method.

Date: Mon, 30 Dec 2019 09:38:46 +0530
From: <xxxx@xxxxxxxx.com>
Return-Path: <xxxx@maildomain.com>
To: xxxx@xxxxxx.com
Subject: =?ISO-8859-1?Q?=xx=65=xx=7xx6=xx=x0=x1=7x0=70=xxx=69=6xx=61=7x4=6x=6x=xE?=
Reply-To: <xxxx@xxxxxxx.com>
User-Agent: CodeIgniter
X-Sender: xxxx@xxxxxxxx.com
X-Mailer: CodeIgniter
X-Priority: 3 (Normal)
Message-ID: <xxxxxxxx@xxxxxx.com>
Mime-Version: 1.0

Content-Type: multipart/alternative; boundary="B_xxx_5e09xxxxxxxxx"

This is a multi-part message in MIME format. Your email application may not support this format.

--B_xxxx_5e0978xxxxxx
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit

I will be absent tomorrow

--B_xxxx_xxxxxxxxxxxx
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

I will be absent tomorrow

--B_xxx_5xxxxxxxxx--

I have tried the following solutions:-

1. Enabled access for less secure apps.

2. Changed host from smtp.gmail.com to ssl://smtp.gmail.com

3. enabling openssl in php.ini file

Some answers suggest that this issue might be generated because 2-factor authentication enabled in the account if it so we have to follow some steps mentioned in the google help page(for Gmail). In my case, 2 factor authentication was not enabled so I ruled out that possibility.

Answer 1

After communicating with google I got many suggestions(not a specific answer). They requested me to try some steps. One of the suggestions was enabling IMAP access and it's solved my issue. In case you want to try this remedy please goto Gmail inbox and follow the following steps.

Step 1:

Step 2:

Step 3: