I have stopped sending “attachment files” via my Gmail messages for a long time already. Instead of sending attachments in my messages, I include a link that could open a specific file from one of my online folders (“cloud storage”).
Recently I had no choice but had to send a 20-MB file as an attachment in an email message. After sending the message I checked my storage usage and only at that time I noticed that my Gmail storage has increased from 10GB to 15GB!
Information below is quoted from Wikipedia (about Gmail service):
The Gmail service currently provides more than 15 GB of free storage per account. Users can rent additional storage (shared between Picasa Web Albums, Google Drive and Gmail) from 100 GB (US$4.99/month) to 16 TB (US$799.99/month), but only 15 GB of this additional storage will apply to Gmail, in effect limiting Gmail storage to 30 GB total. On April 1, 2005, the first anniversary of Gmail, Google announced an increase from 1 GB. Georges Harik, the product management director for Gmail, stated that Google would “keep giving people more space forever.”
On April 24, 2012, Gmail announced the increase of free storage in Gmail from 7.5 GB to 10 GB (“and counting”) as part of the launch of Google Drive. At the same time, Gmail users became unable to upgrade the size of their e-mail inbox beyond a 30GB limit, irrespective of their price plan.
On May 13, 2013 Google announced the merge of their free storage across Gmail, Google Drive, & Google+ Photos allowing users up to 15GB of free storage to use across their accounts.
[Quoted from Wikipedia.]