Add avatar to email with SES

These avatars shown in email clients are not sent as content of the email. Each provider has its own way of resolving avatars (see blow).

If you would use a custom email domain in combination with SES you would get the avatar handling of the email domain provider.

gmail: https://stackoverflow.com/questions/9620366/send-email-with-an-avatar#:~:text=The%20avatar%20displayed%20in%20Gmail,picture%20it%20will%20be%20displayed.&text=This%20works%20in%20gmail.

outllook: https://answers.microsoft.com/en-us/outlook_com/forum/all/how-do-i-show-my-photo-in-my-outgoing-outlook/b3b51308-4763-4eb1-9f87-c11da6c2cd8e