Sending photos from a smartphone to email is quite simple. Typically, you will need two apps: one to browse your photo library and another to send the email. On Android phones, you can use the Gmail and Photos apps (or the photo library app you usually use). For iPhones, the Mail and Photos apps are used.
Steps
Sending Email on Android

Ensure that the photo you want to send via email is saved on your phone. First, open the control panel by clicking on the arrow button at the bottom left. Choose the photo library and open the desired photo.

Tap the share icon and select the email app you wish to use. The share button looks like two small arrows forming a circle. Once you tap this icon, several options will appear based on the digital accounts linked to your phone.

Choose the photo you want to send via email. After selecting the email option, the image browsing screen on your phone will appear. Simply tap the photo you wish to send.

Once you've selected the photo, press the next button. The selected image will be transferred to a new window to attach it to the email.

Compose the email and send it. Enter the email address and message you wish to send by tapping the appropriate fields. You can also add a subject to the email.
Sending Email on iOS for iPhone

Open the Photos app and locate the photo you want to send via email. The app icon looks like a multi-colored flower. To scroll up or down, swipe on the screen.

Select the photo. Tap 'Select' at the top right of the screen, then tap one or more photos you wish to send.

Tap the share icon and attach the photo to your email. The share button is a square with an upward arrow located at the bottom left of the screen. After tapping it, select 'Email photos'.

Compose the email. After tapping the email icon, a new email window will appear. Write the message content and add a subject for the email.

Add a contact. Tap the 'To:' field if the cursor is not there yet. Enter the contact information you want to send the email to.

Send the email. Once all photos are attached, press the send button located at the top right corner of the screen.
Advice
If your mobile data plan is limited, it's better to send photos over a WiFi connection to avoid exceeding your data limit. If you're using a basic phone, use the corresponding button on the keypad to open the email app and compose the message. On Windows phones, open the App List and select Photos. The Photos app has an icon with a white square and a green dot. Choose the photo or video you want to share, tap the Share button (a circular icon with a recycle symbol), and finally select the email share icon to compose the email.
Warning
The number of photos you can send depends on your device's capabilities. Don't forget to double-check the recipient's information before sending to avoid sending personal photos to colleagues by mistake.
