When you save email conversations to OneDrive, you can select from  the following options for attachment filename formats:

1. email message filename – attachment_name
2. attachment_name
3. date attachment_name
4. [from] date attachment_name
5. [to] [from] date attachment_name

email message filename – attachment_name

For example, if you select one email conversation which has two attachments:

…each attachment is saved using the email message filename – attachment_name format:

attachment_name

For example, if you select one email conversation which has two attachments:

…each attachment is saved using the attachment_name format:

date attachment_name

For example, if you select one email conversation which has two attachments:

…each attachment is saved using date attachment_name format:

[from] date attachment_name

For example, if you select one email conversation which has two attachments:

…each conversation is saved using [from] date attachment_name format:

[to] [from] date attachment_name

For example, if you select one email conversation which has two attachments:

…each attachment is saved using [to] [from] date attachment_name format: