A couple of bug reports for your TalkTalk Mail team, both related to Mailto: links.
First is for the TalkTalk Mail app on android. When the app is sent a Mailto: link of the form Mailto:localpart@domain?subject=TalkTalk App Feedback the entire string shown in red is used as the Send to address and the Subject line is not separated out to fill the Subject of the email. The email address is therefore not recognised as valid.
Works fine with other Mail apps. Try in association with the MyTalkTalk app as shown here.
Frustrating for anyone wanting to leave feedback on the MyTalkTalk app using the TalkTalk Mail app. Might have to use on (sic) of the other channels!
Non valid email address so the user has to manually edit the address and add the subject line.
OS: Android Version: 6.0.1
MyTalkTalk App version: 3.0.291
TalkTalk Mail version: 2.0
Next is for the desktop version of TalkTalk Mail. When using Mailto: links the addressing works fine but the Send to name displays the link text.
The underlying email address is fine so the messaging works. With other email clients the display of the Send to name is normal but in TalkTalk Mail the link text is displayed. Odd.