Click on the paper clip-icon above the text field.
Depending on the location of the file you want to add, click Add Attachment from Hard Drive or Add Attachment from Cloud.
Select the file you would like to attach.
You may select multiple files by holding the
Ctrl key and simultaneously
clicking on a file name.
Click Attach or Open.
If necessary, you can attach additional files by clicking the paperclip icon
Afterwards, send the email as usual.
Attaching large files via sharelink
If your attachment exceeds the size limit, you can still send it via the GMX
Open the GMX
Select the file and then click on Share.
The share is created.
Click on Send link via e-mail.
The sharelink is automatically added to the email.
Enter the recipients address and edit the email's content. Click on
Send to send out your email.