post - mail
‘post’ and ‘mail’ as nouns
The public service by which letters and parcels are collected and delivered is usually called the post in British English and the mail in American English. Mail is also sometimes used in British English, for example in the name Royal Mail.
Winners will be notified by post.
Your reply must have been lost in the mail.
British speakers usually refer to letters and parcels delivered to them as their post. American speakers refer to these letters and parcels as their mail. Mail is also sometimes used in British English, especially in phrases such as junk mail and direct mail.
Has the post arrived yet?
I would never open someone else's mail.
In both British and American English, mail is used to mean ‘email’.
I switched on my laptop to check my mail.
Did you get that mail I sent you this morning?
In both British and American English, post is used to refer to a comment or message that someone puts on a website.
I read his latest post on his blog.
Don't use ‘post’ or ‘mail’ to refer to the amount of money that you pay to send a letter or parcel. In both British and American English, this money is called postage.
Send £1.50 extra for postage and packing.
‘post’ and ‘mail’ as verbs
British speakers talk about posting a letter or parcel. Americans usually say that they mail it.
The letter had already been posted.
She mailed the picture to a friend.
In both British and American English, you can say that someone mails something to mean that they send it by email.
I'll mail it to you as an attachment.
He mailed to cancel the meeting.
In both British and American English, you can say that someone posts on or posts something on the internet or on a website, to mean that they put a message, comment, or item there.
She regularly posts on a music blog.
I posted the photo on my Facebook page.