Gmail API 會受到用量限制的約束，這會限制可呼叫 API 方法的頻率。限制是以配額單位定義，這是代表 Gmail 資源用量的抽象測量單位。系統會同時套用兩項用量限制：每個專案的用量限制和每位使用者的用量限制。下表列出這些使用限制的詳細資料：
| 用量限制類型 | 限制 | 超出原因 |
|---|---|---|
| 每項專案的頻率限制 | 每分鐘 1,200,000 個配額單位 | rateLimitExceeded |
| 每位使用者頻率限制 | 每位使用者每分鐘 15,000 個配額單位 | userRateLimitExceeded |
按方法的配額使用量
請求所消耗的配額單位數量會因所呼叫的方法而異。下表概略說明每種方法的配額單位用量：
| 方法 | 配額單位 |
|---|---|
drafts.create |
10 |
drafts.delete |
10 |
drafts.get |
5 |
drafts.list |
5 |
drafts.send |
100 |
drafts.update |
15 |
getProfile |
1 |
history.list |
2 |
labels.create |
5 |
labels.delete |
5 |
labels.get |
1 |
labels.list |
1 |
labels.update |
5 |
messages.attachments.get |
5 |
messages.batchDelete |
50 |
messages.delete |
10 |
messages.get |
5 |
messages.import |
25 |
messages.insert |
25 |
messages.list |
5 |
messages.modify |
5 |
messages.send |
100 |
messages.trash |
5 |
messages.untrash |
5 |
settings.delegates.create |
100 |
settings.delegates.delete |
5 |
settings.delegates.get |
1 |
settings.delegates.list |
1 |
settings.filters.create |
5 |
settings.filters.delete |
5 |
settings.filters.get |
1 |
settings.filters.list |
1 |
settings.forwardingAddresses.create |
100 |
settings.forwardingAddresses.delete |
5 |
settings.forwardingAddresses.get |
1 |
settings.forwardingAddresses.list |
1 |
settings.getAutoForwarding |
1 |
settings.getImap |
1 |
settings.getPop |
1 |
settings.getVacation |
1 |
settings.sendAs.create |
100 |
settings.sendAs.delete |
5 |
settings.sendAs.get |
1 |
settings.sendAs.list |
1 |
settings.sendAs.update |
100 |
settings.sendAs.verify |
100 |
settings.updateAutoForwarding |
5 |
settings.updateImap |
5 |
settings.updatePop |
100 |
settings.updateVacation |
5 |
stop |
50 |
threads.delete |
20 |
threads.get |
10 |
threads.list |
10 |
threads.modify |
10 |
threads.trash |
10 |
threads.untrash |
10 |
watch |
100 |