Mail Drop - fail

Kenneth,

i experienced the same problem since installing Catalina and could solve it with following actions:

The maximum size of files you can send as a mail attachement is determined by your mail provider. If it is less than 20MB then you have to adapt the default minimum size parameter for maildrop. By default it is set to 20MB. You can verify that in the Terminal app.

Start Terminal, and enter: defaults read com.apple.mail minSizeKB

This will return the set value.

If you want to change that to e.g; 10 MB then enter: defaults write com.apple.mail minSizeKB 10000  

It may also help to compress the file or folder you want to send. You can do that by creating a zip file (contol+select the file and chose compress).

Also in Mail>Preferences>Accounts deselect the option to use maildrop for that account. Doing this will generate a selection window asking if you want to use Maildrop, when the file exeeds the max allowed by your provider.

You can then select the Maildrop option.

Finally close mail and log-out from iCloud, then log-in to iCloud again and start the Mail app.

These actions solved the problem on my system.

Hope this helps.

Hi Kenneth Day,

Thank you for using the Apple Support Communities. 

We understand that you can't send emails with attachments and we're happy to help!

“Some mail servers reject messages that exceed a certain size. If your message includes attachments, use Mail Drop or try resizing image attachments."

"You can use Mail Drop to send files that exceed the maximum size allowed by your email account provider. Mail Drop uploads large attachments to iCloud, where they’re encrypted and stored for up to 30 days.

• If you have an iCloud account and you’re signed in to iCloud when you click Send, Mail automatically sends the attachments using Mail Drop. Mail Drop attachments don’t count against your iCloud storage.
• If you don’t have an iCloud account, or if you’re not signed in, Mail asks you whether to use Mail Drop (to always use Mail Drop select “Don’t ask again for this account”).

If a recipient uses Mail in OS X 10.10 or later, the attachments are included in your message. For other recipients, your message includes links for downloading the attachments, and their expiration date. 

You can turn Mail Drop on or off for an account. Choose Mail > Preferences, click Accounts, select the account, click Advanced, then select or deselect “Send large attachments with Mail Drop.”

See the Apple Support article Mail Drop limits."

See also

Add attachments to emails

If you can’t send emails in Mail on Mac

If people don’t receive emails you send using Mail on Mac

We hope this helps.

Take care.