I use a pic of my late Samoyed dog as "My Picture" when sending Gmail. I had to have him put down (vet's strong recommendation) because his hip dyspepsia and multi-organ failure had my poor dog in chronic pain. Analgesics just did not significantly relieve his pain. While the pic is very sentimental to me, that very cute image is not appropriate for business emails. I know that I can delete the image, when dealing with formal emails, and then upload it again. But I am hoping there is a way to temporarily switch the "My Picture" option off when sending formal emails, and then turn it back on for more casual emailing.
No, there is no way to temporarily off My Picture in Gmail.
There are only two options. See Gmail Help:
Visible to everyone: Anyone who you email, or who emails you, can see your picture.
Visible only to people I can chat with: Only people you've given permission to chat with you or see when you're online can see your picture.
In your case if you don't want remove picture, choose the second option.