Google's email service Gmail that has nearly 1.5 billion monthly active users turned 15 on Monday and the company plans to make it more assistive.

Today, Gmail allows 15GB free storage. Users can receive emails up to 50MB in size, including attachments, while they can send emails up to 25MB in size. In order to send larger files, users can insert files from Google Drive into the message.

"Over the years, Google also improved Gmail's spam filtering capabilities and today, using Artificial Intelligence (AI), Gmail blocks nearly 10 million spam emails every minute," the company said in a statement.

The main new feature is the Schedule Send feature, which allows you to schedule emails to be sent at a particular time. The feature allows you to send an email next morning, next afternoon, on a certain day, or you can simply pick the exact date and time you want to send the email. You won’t have to have the Gmail app open after scheduling the email for it to actually be sent, as that’s all done on the backend.

"Gmail's tabbed inbox feature was the first of its kind, helping you organise messages by category, so you can see what's new at a glance. AI-powered features like Smart Reply and Nudges helped you reply faster and stay on top of your to-dos,' the company added.

Google has included more languages including Spanish, French, Italian and Portuguese to its "Smart Compose" feature on Android and would reach iOS users soon.

Gmail is also improving its Smart Compose feature. The feature was previously limited to Pixel 3 devices and it’s now coming to all Android devices, with an iOS release expected soon as well. Smart Compose also now remembers what kind of greetings you prefer to use on your emails.

"It will personalize suggestions for you, so if you prefer saying "Ahoy," or "Ello, mate" in your greetings, Smart Compose will suggest just that. It can also suggest a subject line based on the email you've written," the company added.

To let users take action without having to leave their inboxes, Google would now allow them to respond to comment threads in Google Docs.

"This way you don't have to open a new tab or app to get things done," said Google.