OS X 10.8.5 is Mountain Lion. In the future posting in the correct forum gets the best results.
Under Windows in the Menu bar select Connection doctor. You will see green to indicate a connection and red to show there is a problem. You can click on more details button, but with multiple accounts this is often hard for some users to read result. Except for iCloud account you'll see two entries for each account 1) receiving and 2 SMTP for sending.
Sending issues usually involve SMTP settings.
Mar 01, 2013 This has allowed both Pop and Smtp settings to work on the computer running Mac OS 9.2. Gmail would not work, nor any of the other possibilities you suggested. Most of the standard browsers cannot be used with any Mac operating system earlier than OS 10-and Gmail, etc., insist on a later browser than what I have. Fortuntately, Yahoo did not.
EDIT SMTP SETTINGS
In Accounts window > Outgoing Mail Server SMTP: select to Edit SMTP Server list.. from popup
Gmail Messenger For Mac Os X High Sierra Download
Select account in the list.(It's not uncommon to find extra SMTP servers listed. When you remove account, Mail does not delete the smtp info. You might need to do some clean up in the list to remove the extras.)
Under Advanced Tab:
Apple defaults to the default ports (25,465, 587) but some servers prefer a custom port. Check to see what port they recommend. Gmail for example likes 465, Outlook.com 587.
Verify if your server require SSL. Both Gmail and Outlook.com require SSL.
Add password if it is blank. (If you have two step authentication setup, you'll need to get an app specific password more info)
Open Connection Doctor under Window in the Menu bar.
Do you see green light now for your account SMTP?
Gmail seems to work best in Mavericks iyou delete and start clean. This involves reviewing your settings in your browser and in Mail. See
Use Gmail with Mavericks Mail **
**(Fair disclosure: NeedHelp4Mac is my site. I may receive some form of compensation, financial or otherwise, from my recommendation or link.)
Jul 8, 2014 2:51 PM
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Mail User Guide
You can include photos, documents, and more when you write messages.
When you attach images or PDF documents, you can mark them up in Mail before you send your message.
Include photos and other files in emails
In the Mail app on your Mac, do any of the following:
Click the Attach button in the toolbar, locate a file (you may need to click the sidebar button to see additional folders), select it, then click Choose File.
You can also drag files from the desktop, the Finder, or an app into your message.
For photos, click the Photo Browser button in the toolbar, then drag a photo into your message. You can also take a photo or scan documents, or add a sketch, using your nearby iPhone or iPad.
By default, Mail inserts images at their actual size. If different sizes are available, you can choose one from the pop-up menu located on the right side of the message header.
Send large email attachments using Mail Drop
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.
Put email attachments at the end of messages
In the Mail app on your Mac, do one of the following:
For the current message: Choose Edit > Attachments > Insert Attachments at End of Message.
For all messages: From the Message viewer, choose Edit > Attachments > Always Insert Attachments at End of Message (a checkmark shows it’s on).
Include or exclude email attachments in replies
In the Mail app on your Mac, do one of the following:
Include or exclude original attachments in a reply: In the toolbar of the message window, click the Include Attachment button or the Exclude Attachment button .
Include or exclude original attachments in all replies: From the Message viewer, choose Edit > Attachments > Include Original Attachments in Reply (a checkmark shows it’s on). To turn it off and exclude attachments, choose the command again (the checkmark is removed).
Send email attachments to Windows users
In the Mail app on your Mac, try these suggestions:
Send Windows-friendly attachments. To do so for all messages, choose Edit > Attachments, then select Always Send Windows-Friendly Attachments. For a specific message, click the Attach button in the toolbar of the new message window, then select Send Windows-Friendly Attachments (if you don’t see the checkbox, click Options in the bottom corner).
Use filename extensions (such as .docx for a Microsoft Word document).
If the recipient sees two attachments (such as “MyFile” and “._MyFile”), the recipient can ignore the file with the underscore (such as “._MyFile”).
To display an attachment (such as a one-page PDF document or an image) as an icon, Control-click the attachment in your message, then choose View as Icon. To show the attachment again, Control-click it, then choose View in Place.
If the message size shown on the left side of the message header is red, the attachments are causing your message to exceed size limits set by your email account provider. Try reducing the number or size of attachments or use Mail Drop.
See alsoEmail a webpage shared from Safari in Mail on Mac