To start a new email conversation, click the Compose button on the toolbar. Type the email address of the people to receive the message in the To text field, and a subject line in the Subject field. You can then type your message in the text area below these. Once the message is ready to send, click Send or type CtrlEnter to send the message.

To show the Cc, Bcc, and Reply-to fields, click the More options button at the end of the To field. Cc allows you to send a copy of the email to other, secondary recipients. Bcc is similar, but the Bcc list is hidden from recipients. The Reply-To field specifies an email address to reply to, if recipients should reply to a different email address than the sender's.

When entering an email address into any of these fields, Geary will provide suggestions from your desktop address book and from previously sent and received email messages. To choose one of these suggestions, simply click on it.

To reply to the currently selected conversation, click one of the Reply, Reply All or Forward toolbar buttons. This will open a new reply or forwarded email composer for the latest message in the conversation.

When replying, the message being replied to will be quoted and copied into the footer of the new reply. This can be deleted before typing a reply by pressing Backspace. Alternatively, text can be selectively quoted by selecting the desired text in a message and clicking Reply or Reply All, only the selected text will be quoted.

To reply to a specific email message, open the message menu in the top corner of the message and choose Reply, Reply All or Forward.

Geary's email composer lets you use text styles such as bold and italic, indent text to quote it, and links to web pages. Simply select the text and click the appropriate button on the formatting toolbar at the bottom of the composer area.

Bulleted and numbered lists can be inserted or removed by clicking the Bulleted list and Numbered list buttons on the formatting toolbar. The level of indentation of list items can be adjusted using the Indent and Un-indent formatting toolbar buttons.

Images can be inserted into rich text messages by clicking the Insert Image button on the formatting toolbar and selecting the image to attach, by dragging an image from the Files application into the email body and then dropping it, or by pasting an image that has been copied to the clipboard from another application.

Documents, music, videos, and other files can be attached to the email by clicking the Attach File button at the bottom of the composer window and selecting the document to attach, or by dragging a file from the Files application to the composer window, and dropping it either on the text fields at the top of the window or on the toolbar at the bottom.

A number of keyboard shortcuts are available in the composer; see for details.

You may specify a signature to be inserted into the footer of email in the composer via the dialog.

Geary supports spell-checking your composed email in one or more languages, as you type. To enable spell-checking, first ensure your computer has spell-check dictionaries installed for the desired languages. Consult your computer's help to determine how to install dictionaries if not present.

To select languages for spell-checking, click the Spell check button on the formatting toolbar, and the language selection popover will appear. Click on a language in the list to toggle it on or off, and click the - button to remove it from the list. If a language does not appear in the list, search for it by typing its name in the search box, then click the + button to add it.

For mail servers that support drafts, Geary will automatically save the message as you type on the server after a short delay.

To edit an existing draft, select the Drafts folder in the folder list, select the message, and click "Edit Draft" in the conversation viewer.

Geary will delete the draft when you send the message.

Geary can also send plain text messages. Press the More options button at the end of the bottom toolbar, then choose "Rich Text" or "Plain Text". Plain text mode is useful when sending email to mailing lists that prohibit rich text (HTML) messages, or when sending email to people that do no use modern clients like Geary.

In plain text mode, text will be automatically wrapped using soft line breaks so that it is no longer than 74 characters wide, and indented text will be wrapped and quoted using a “>” character for each level of quoting.